Add DSL for defining commands (refs #64)
Add :update command (refs #64)
Swap OpenStruct with Virtus in specs

Forgot that OpenStruct behaves differently on jruby and rbx...
Fix for rbx (probably a bug in rbx)
Add Delete command (refs #64)
Merge branch 'master' into command-api

Conflicts:
	lib/rom/adapter/memory.rb
Update CHANGELOG
Add commands.try API
Only rescue from ROM::CommandError
Fix failure proc handler
Fix method-missing behavior in command "try" evaluator
Add "result" option to create command DSL

This allows you to specify whether the command should return a single
tuple or many
Add abstract command classes
Separate command execution logic into execute and call methods
Add :one/:many result support to Update command
Remove redundant Update#call
Add a TODO comment

[ci skip]
Move command factory method to abstract adapter
Default to Hash and empty Proc for input/validator
Add sequel to sql group in Gemfile