Initial changes to get a pared-down editor with some test plugins.

Summary:
static code insertion working

Fixed iframe embed by adding 'allowedContent' to plugin command.

built first draft

added gglspreadsheet.plugin.js

remove gglspreadsheet/plugins.js

config.js location problem, otherwisesaving edits works

altered gglspreadsheet/plugins.js so no more icon errors

Added many basic plugins(youtube, pdf), but still unpolished.

<one-line summary, followed by blank line and full summary>

Moved config.js into release directory

Added missing files to ckeditor to make the toolbar work correctly.

-Added correct icons for new plugins (youtube,gglspreadsheet,pdfs) -Wrote new image plugin 'image2' and replaced image on the toolbar with it. -cleaned up config and build-config

Updated image2 so that can be centered when cursor is on either side (haven't gotten it working for highlighting the image). Added full page toggle option to image2 that is currently being filtered out.

Added icons for custom plugins

Icons added in release directory

icons added in release directory

Test Plan:
- Load an article page
- Click the "edit" cog icon
- Verify the article editor shows up with toolbar, includes icons for
  YouTube, Google spreadsheet & PDF

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.

<see below>

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.

Loaded editor. Saw that toolbar was fixed.

<see below>

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.

<see below>

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.

<see below>

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.

<see below>

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.

<see below>

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.

Reviewers: tom

Differential Revision: http://phabricator.khanacademy.org/D2658
Updates that were suggested on fabricator
Test Plan:
same as previous

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.
edited config and plugins as per requests (cleaning)
Test Plan:
<see below>

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.
removed extra line in toolbars/plugins.js

Test Plan:
<see below>

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.
updated gglspreadsheet, youtube, and pdfs plugins as per Tom's requests.

Test Plan:
same as before

Conflicts:
	dev/builder/release/ckeditor/ckeditor.js
Added clarification in youtube/plugin.js

Test Plan:
<see below>

# --
# For 'Test Plan:', list the commands you ran or process you
#   followed to test this change.
# If this commit is adding to an existing review, delete the
# 'Test Plan:' lines and replace them with 'Review: Kxxx'.