Initial support for API versioning.

Resource version can be specified in resource controller or in one of parents controllers.
Parallel existence of one resource in more versions is supported - they have to be in separated
modules (see example in spec/dummy application).
Merge branch 'master' into api_versioning
Merge branch 'master' into api_versioning

Conflicts:
	lib/restapi/application.rb
Merge branch 'master' into api_versioning
Merge branch 'master' into api_versioning
Merge branch 'master' into api_versioning

Conflicts:
	lib/apipie/application.rb
	lib/apipie/resource_description.rb
	spec/controllers/users_controller_spec.rb
	spec/dummy/app/controllers/users_controller.rb
Restapi->Apipie
Support for API versioning #34

- option to specify default version
- list of versions on the homepage
- api_doc_url and app_info are version specific and can be filled
  in config file or in base controllers
- Apipie::Configuration separated to own file
- added config option debug
- methods are saved in its resource in hash
  no Apipie.method_descriptions anymore
- added 'version' argument to rake tasks, using default version if not specified
Small code readability improvements #34

+ it is now possible to turn of markup, we should use this when generating cli client.
Preserve methods order #34

Also there was quite a mess in symbol vs string use
Suggest: use symbols as hash keys
         use strings everywhere else
Extract configuration to separate file
Ignore listed controllers or actions from documentation
Merge pull request #72 from iNecas/exclude

Exclude certain controllers and actions from docs
Merge remote-tracking branch 'origin/master' into api_versioning

Conflicts:
	app/controllers/apipie/apipies_controller.rb
	lib/apipie/apipie_module.rb
	lib/apipie/application.rb
	lib/apipie/client/generator.rb
	lib/apipie/configuration.rb
	lib/tasks/apipie.rake
	spec/dummy/config/initializers/apipie.rb
Ensure clearing last dsl values after method definition

Using single place for resetting the values to avoid unintentional
results when forgetting clearing some value. Also, some methods
were doing more than expected.
api_version keyword

Specify what version does the method belong it. One method can belong
to more versions.
Improved versions support

Controllers and methods can be part of more versions.
Remove the client generator from Apipie itself

It's hart to make the client code generation generic enough to fit
all the projects (including authentization, versioning etc.).

Therefore, I'm removing the code itself from this gem. Preferred way
is to use the apipie.json data that this gem provides and use that to
generate the code that fits the project needs.

An example of a client generator using the API is here [1]

[1] - https://github.com/mbacovsky/foreman_api
Fixing the doc's reloading in Rails 3.2
Fix test regressions