package.json: add a repository field

NPM kept complaining about this repository field missing.
package.json: use devDependencies throughout

None of the dependancies listed are actually required for *using*
TinyMCE, but merely when building it. The distinction is mainly an
issue of clarity and correctness, as TinyMCE isn't used as a Node
package proper.
package.json: prevent publishing of TinyMCE to NPM

NPM isn't a node package as such, and thus isn't terribly useful as a
dependancy. As a result, it probably shouldn't be published to NPM,
and this flag prevents it.
Fixed so the max characters for width/height is more than 3 in the media and image dialogs.
Fixed bug where the started state of the spellchecker wouldn't be properly handled.
Removed prevent call since it blocks caret placement on WebKit.
Fixed so that the ComboBox control can have a submenu.
Fixed bug where WebKit/Blink would scroll to the top of editor if the height was more than the viewport height.
Fixed a but where WebKit/Blink clones elements when images are floated.
Merge pull request #307 from danchr/package-json

Minor tweaks to ‘package.json’
Fix for allowing a user to drop content into a noneditable with the noneditable plugin