Batch Update of Nginx configuration

This update includes many improvements for faster regex (by disabling back-references where possible).

It also introduces the correct and much faster support for domain aliases and redirects.

Security is now turned into strict mode, so only some known Drupal php files are allowed.

We introduced support for some newer modules, like imagecache in D7 - the files/styles path.

Also global Nginx configuration is now better tuned for performance and stability.

There are also a few fixes for URLs by default used in Aegir, like support for domains with .pl and .info extensions.

It is a result of many support requests and issues filled by Nginx users, so there were many tiny patches/commits in the meantime so I didn't consider them enough important to submit to the master. Also, in fact probably 90% of this commit is a result of two commits we made in our repo in the last 3 days, so it is not really as fragmented as it would be if submitted in parts, but OK, I will do that in the future, to avoid "too heavy changes" impression.

As promised, here is next commit for review: http://gitorious.org/aegir/provision/commit/a79e2fb96864c157e5b8cbbd00c7...

It simply re-orders locations in the shared Nginx configuration files for better performance and resolves small issue with "scripts" in the URL filter, introduced in previous, big commit. Also, the authorize.php file is added to the list of allowed php files for d7 compatibility.

Both commits have been tested and are used in production already.

Next commits to review:

Enable open_file_cache in Nginx for better performance.
http://gitorious.org/aegir/provision/commit/c6e0abff21ca61a4acdb798c3535...

Remove images from gzip_types and lower gzip_comp_level to optimal value: 5.
http://gitorious.org/aegir/provision/commit/6f0b24b55b2187e8df4c58a24899...

Fix for broken imagecache support after recent locations changes.
http://gitorious.org/aegir/provision/commit/935fc341badabcb7a737b4e39b8f...

Next commit to review:

Fix for broken pop-ups in the wysiwyg editors.
http://gitorious.org/aegir/provision/commit/483d8718dacd59a14067ebf13f24...

Next commit to review:

Fix for wysiwyg editors support in the Nginx config + do not use php-fpm to serve static files from wysiwyg libs:
http://drupalcode.org/sandbox/omega8cc/1074910.git/commit/88f7cf0

Next commit to review:

(major bug) Fix for restricted access to private files in the Nginx configuration:
http://drupalcode.org/sandbox/omega8cc/1074910.git/commit/f1975d1

Uh, I see I have even more those whitespace still. Thanks for pointing that out.

Cleaning trailing whitespaces in the Nginx config files:
http://drupalcode.org/sandbox/omega8cc/1074910.git/commit/48d3f95

Rerolled waiting commits:

Fix for wysiwyg editors support in the Nginx config + do not use php-fpm to serve static files from wysiwyg libs:
http://drupalcode.org/sandbox/omega8cc/1111100.git/commit/91a3027

Fix for restricted access to private files in the Nginx configuration:
http://drupalcode.org/sandbox/omega8cc/1111100.git/commit/b01c498

Cleaning trailing whitespaces in the Nginx config files:
http://drupalcode.org/sandbox/omega8cc/1111100.git/commit/28eb054

One minor fix and two new features added:

Fix for Nginx configuration: if the file does not exist, send 404 error instead of back to parent location.
http://drupalcode.org/sandbox/omega8cc/1111100.git/commit/38f2aa4

Add support for AdvAgg module in the Nginx configuration.
http://drupalcode.org/sandbox/omega8cc/1111100.git/commit/ccb98d6

Add support for robotstxt module in the Nginx configuration.
http://drupalcode.org/sandbox/omega8cc/1111100.git/commit/2066eb1