xapian 7.x-1.0

Changes since DRUPAL-7--1-0-RC1:

• minor: Better credits.
• task #1005908 by pillarsdotnet, marvil07: Better strings for the module.
• task #958360 by marvil07: Re-organize modules in the project and document the difference between both.
• feature #923752 by marvil07: Integrating with search_api().

  This patch creates a new submodule search_api_xapian that implements a
  search backend for the Search API[1].

  It provides two Search API servers: one for handling a local xapian
  database and the other for handling a remote xapian database running by
  xapian-tcpsrv.

  1: http://drupal.org/project/search_api

• task #958360 by marvil07: Re-organize modules in the project and document the difference between both.
• bug #1042704 by pillarsdotnet: Fix compatibility of xapian and search_api_xapian() hook_requirements() implementations.
• minor: Remove CHANGELOG.txt as I am pretty bad maintaining it.