Add MenuPresenter specs.
Remove the .dev from version.
Add 2.0.x -> 2.1.x upgrade guide and reorder other guides located in the same folder.
Merge pull request #2326 from refinery/upgrade_guide

Add 2.0.x -> 2.1.x upgrade guide and reorder other guides located in the same folder.

[ci skip]
Merge pull request #2319 from refinery/menu_presenter_specs

Add MenuPresenter specs.
Remove notifier gems.

If the user wants to or needs additional gems like notifiers, runners
etc - add them to .gemfile.
Merge pull request #2327 from refinery/remove_notifier_gems

Remove notifier gems.
Defer to gemspec and non git sources where possible.
Support jquery-rails > 2.0

This is needed to be compatible with newer versions of eg. Spree
Completely removed jquery.corner and jquery.migrate scripts.
Add "What's new in 2.1.0" guide.
Merge pull request #2329 from refinery/whats_new_guide

Add "What's new in 2.1.0" guide.
Update "Overriding views" guide.
Use jquery-rails 2.3.0 band
Fix adding page parts and reordering.
Merge pull request #2328 from refinery/pull_2299

Merged #2299 and removed jquery cornering and migrate scripts.
Enable setting page view template by default.
Merge pull request #2331 from refinery/enable_page_layouts_by_default

Enable setting page view template by default.
Fixed spelling error in contributing.md

Changed 'Plase' to 'Please'
Merge pull request #2334 from shivamd/master

Fixed spelling error in contributing.md