Added the possibility to update button icon after it's been rendered.
Merge pull request #262 from tractionsoftware/native_contextmenu

Show native contextmenu with ctrl key
Adds the mac_ctrl_key=ctrl/cmd/both preference so that mac users can have their ctrl keys back. The default is set to 'both' to match existing behavior, but 'cmd' will work like other editors on the mac. For example, Ctrl-A will move the cursor to the beginning of the line while Cmd-A will select the entire buffer.
Merge branch 'master' of https://github.com/tractionsoftware/tinymce

y,
Merge branch 'master' into teampage