add support for installments(parcelamento)
Change Comission raised errors to new MyMoip::Comission class
New InvalidCreditCard, InvalidInstruction and InvalidPayer exceptions
Merge branch 'exceptions'
Inherit new MyMoip exceptions from MyMoip::Error
Remove unnecessary exception messages
Version bump to 0.5.0
Regenerate gemspec for version 0.5.0
Merge pull request #24 from raphaelcosta/master

Adicionar suporte a Parcelamento
Require test suite compatibility with Ruby 2.0
gitignore Gemfile.lock file

As advised from Yehuda Katz's
http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/
Include CHANGELOG entries for 0.6.0
Document installments use in README file
Revert "gitignore Gemfile.lock file"

Restore Gemfile dependencies due Jeweler's bug generating a gemspec
file requiring the gem ifself.

This reverts commit 56adcbd452bee33f3afd60d7d46087db37350463.

Conflicts:
	README.md
Version bump to 0.6.0
Regenerate gemspec for version 0.6.0
Change gem's description
Update README and gemspec files due gem's new description
Merge remote-tracking branch 'origin/master' into purchase-class

Conflicts:
	README.md