This commit creates structure for Action View gem and is first of a
series of commits extracting Action View from Action Pack.

This reverts commit c24528fb.

All ActionPack and Railties tests are passing. Closes #8891.

[Carlos Antonio da Silva + Santiago Pastorino]

It includes security bug fixes and changes the initialization of
Rack::File to accept a hash, otherwise generating warnings.

See 295806e1 for the warnings fix.

Move the Journey code underneath the ActionDispatch namespace so
that we don't pollute the global namespace with names that may
be used for models.

Fixes rails/journey#49.

Obviated by rubygems/rubygems@486ed83cc8e706069213c5d406122f4cfcca9e7f

This reverts commit bb8923de.

RG2 packager expects each spec.files path to be a file and bombs when it tries to tarball a dir.

May revert if rubygems/rubygems#413 is accepted.

Organized the gemspec files a bit.

 * Made quotes more consistent (single quotes dominated, so I used
   that).
 * Moved license line down a line, separating it logically, and removed
   the extra whitespace before its = operator.
 * Minor whitespace fixes.

There are some Action Pack tests for regressions from 3.1 that require
a later version of Journey to pass so bump to the current version.

ActiveModel is used in ActionPack for ActiveModel::Naming for a few,
mostly optional aspects of ActionPack related to automatically converting
an ActiveModel compliant object into a key for params and routing. It uses
only three methods of ActiveModel (ActiveModel::Naming.route_key,
ActiveModel::Naming.singular_route_key and ActiveModel::Naming.param_key).

This version brings bug fixes for performance and caching.

Versions prior to 1.1 delete the If-Modified-Since and If-Not-Modified headers when
config.action_controller.perform_caching is true. This has two problems:
 * unexpected inconsistent behaviour between development & production environments
 * breaks applications that use of these headers