Release 1.1.1

Summary
This supported bugfix release corrects the inifile section header
detection regex (so you can use more characters in your section titles).

Bugfixes
- Correct section regex to allow anything other than ]
- Correct `exists?` to return a boolean
- Lots of test updates
- Add missing CONTRIBUTING.md
Merge pull request #119 from hunner/release_1.1.1

Release 1.1.1