Adding select form to choose format display (teaser or full)

I created a patch to offer possibilty to choose if the content in the block is displayed as teaser or full node.

I also added the patch for the bug with the language test.

Please review it and your comments are welcome :-)

2 files to patch:
nodeasblock.install : Added a field (teaser) in the table {nodeasblock}
nodeasblock.module : patch form and load