Fixing failing Travis.

Also, i have locked the testing version of Ruby for now to 1.9.3. The problem with testing the SDK on multiple versions is that Travis tests them basically in parallel, therefore causing validation errors (e.g. at the same time two ruby test suites create a directory called *test_directory* causing the second one to fail because of the uniqueness validator. Will see what's best to do later.
Any reason for this change?