Fix for the Insert Color command

[fredb]

Workaround to make the Insert Color command work again. It uses "Applescript Runner" to launch the picker as TM2 can't send an applescript command to itself for now (see this issue).

Beside that, the only differences are:

• It needs to switch focus away and back to TM to bring back focus to the document. (using open -a as we can't use tell app "TexMate"…)
• Small changes so we can use the command when writing a color for the first time, with no hex color selected (it puts back : or ; and spaces if they are included in the scope)

Due to these changes, the command is self contained and doesn't use the TextMate::UI.request_color() anymore.

The commit messages aren't precise enough, when I stupidly started with the command alone they were obvious, but I had to export and patch the bundle to send the pull request. Sorry about that. Feel free to do what it takes to clean it if you want.

[infininight]

Pulled thanks. Finessed the commits a bit to be cleaner. :)