Ruby 2.2 compatibility

Common Errors and solutions

1. tests complaining about 'skip'

: NoMethodError: undefined method skip' for #<TestFoo:0x007fb75484f158>

Two solutions Reference

2. Ruby2.2 reports NameError: uninitialized constant <Object>::<Something> while Ruby2.1 works

3. Ruby2.2 not detecting sqlite3 gem and suggests to add it to Gemfile

ruby-sqlite3 needs to be rebuilt with Ruby2.2 support