[mrbgems] GEM Dependency Check

[doc] Add minimal build configuration

[TestEnv] Fallback print method

In relation to #1225.

Adds a minimal build configuration for libmruby which contains as less as possible.

Cleanup hash

Add type check in Hash#merge!

Adding a few more respond_to tests

fix typos.

sort mrbgem's mrblib/*.rb files

 - https://github.com/mruby/mruby/commit/5de9a8cc50052db105ea8ba06d64b95cb1b57db1

First strik on GEM Dependencies

Push Copyright year up to 2013