Fixed exception on unknown parameter type

Raises exception for parameter types that doesn't match any of validators.
nil parameter is still allowed.
Fix for concern substitution spoiling parameter names

Concern substitution was spoiling parameter names that could not be replaced.
Eg. parameter :name ended up as :":name" at the function's output.
Good bye 1.8.7 and 1.9.2 in Travis

We care only for 1.9.3 and 2.0.0 right now
Merge pull request #137 from tstrachota/missing_validator

Fixed exception on unknown parameter type
Merge pull request #139 from tstrachota/concerns

Fix for concern substitution spoiling parameter names
Correct expected_type for parameters taking arrays
Merge pull request #136 from tstrachota/type_validator

Correct expected_type for parameters taking arrays
Merge remote-tracking branch 'parent/master'
Version bump and gemspec change.

These are really changes for my personal preference