Fix bug with page part deletion.

Due to recent jquery-ui version bump tabs widget api has changed
and we were still using old api.
Find proper id of active tab.
Add more checks to ensure proper page parts are deleted.
Fix image resizer in the image picker. Closes #2345.

Some code was changed in e539215f32cd9f190210c91c5da2057b0106b5bd and
it appears that two occurances of set_image wasn't renamed to
toggle_image.
Merge pull request #2351 from refinery/issue_2349

Fix bug with page part deletion.
Use new Bundler syntax.
Edge template requires edge decorators.
We don't need to gsub jquery-rails version now that we rely on it
No need for edge because refinerycms-acts-as-indexed is released.
Only bundle once unless therubyracer is also required.
Fixes #2352 by aborting when execjs can't be used.
Merge pull request #2355 from refinery/abort_when_execjs_not_present

Fixes #2352 by aborting when execjs can't be used.
Updated installation templates for version 2.1.0
Noted recent changes.
Moved versions away from git
Updated generator_spec and removed commented debuggers.
Work around JRuby issue with pluck.
Merge pull request #2356 from refinery/release

Things needed for 2.1.0 release
Merge branch 'master' of https://github.com/refinery/refinerycms