Test against latest version of Ruby 2.1

- update README to reflect this
Fix for not loading options properly from percona config

- always use a HashWithIndifferentAccess for database_config so symbol/string keys don't matter
- added tests for loading run_mode from config
  - make sure it does the right thing regardless of how it's specified in the yaml file
- bump version to 0.1.3
Merge pull request #2 from steverice/0.1.3

Additional testing, load run_mode properly