Add .Thumbs.db to .gitignore.

Windows generates .Thumbs.db files for folders. GIT should ignore those.
Merge pull request #2979 from braingourmets/task/gitignore

Add .Thumbs.db to .gitignore.
Update the Rails versions in .travis.yml to the latest versions.

* change 4.0.2 to 4.0.3
* change 3.2.16 to 3.2.17
Merge pull request #2983 from braingourmets/task/rails-4.0.3

Update the Rails versions in .travis.yml to the latest versions.