Remove rgeo from Gemfile (in gemspec)
Relax activerecord dependency to support 4.0
Add appraisal for activerecord 4.0

Generate appraisal files
Update Travis with supported platforms

Drop ruby 1.8, 1.9, jruby
Update 2.1 to 2.1.1
Add rbx2 (rubinius 2.2.5+)