FindSoci.cmake: fix couple of minor issues

- there is no SOCI_${plugin}_LIBRARY variable, correct name is
  SOCI_${plugin}_PLUGIN
- variable names, not variable expansions, shold be placed into
  confitional statements like IF()
Bumped version number to 3.2.0
Merge pull request #40 from mloskot/master

Bumped version number to 3.2.0
Merge pull request #36 from avg-I/cmake/find-soci

FindSoci.cmake: fix couple of minor issues
In tests, fixed warning: comparing floating point with == or != is unsafe. The warning is still reported for is_infinity_or_nan() in MySQL backend, see relevant comment in mysql/common.h
Merge branch 'master' of https://github.com/SOCI/soci
For Visual C++, defined std::strtoll in terms of _strtoi64(). Fix for issue #27 and related to pull request #37.
Merge pull request #43 from mloskot/master

For Visual C++, defined std::strtoll in terms of _strtoi64()
Fix for #44 - Placeholder at the last position of statement causing crash

Patch received from Daniel Beaudoin (Optel Vision) on 23/07/2012)
Merge remote-tracking branch 'upstream/master'
Fixed #48 - Incorrect assertion in postgresql::get_error_details. Patch received from Fedor Trushkin.
Added _build* pattern to .gitignore.

There is build in top-level directory of the source tree, so we can't
ignore build globally. To make in-source build subfolders usable without
annoying Git prompts about unstaged changes, we can use _build and its
variants (_build-{branch}-{build type}, etc.). It will be ignored.
Update .travis.yml to install unixodbc-dev -  #49
Added Travis CI build status badge
[SQLite3] Report test6() as skipped
Merge branch 'master' of github.com:SOCI/soci
Renamed README to README.md and switched format to Markdown.
Merge branch 'master' of github.com:SOCI/soci