Sperate image alt tag and title

When using the TinyMCE interface to insert/edit images there is only one field for the image name witch sets both the title and meta text.  This is not logical though as there are many cases when users may want different meta text then hover/title text, or more likely not want any title text at all.  

This can technically be fixed by going into the html code of the resulting property and removing/changing the unwanted title attribute but this is efficient.  Also if the popup control is used again to adjust the text of the image the title take will again be updated/recreated.

This patch simply adds a separate text field for the image title that defaults to blank. (The alt still defaults to the  media node name like before.) Thus a user can set the title as desired of leave it blank if they don't want titles.

![screen shot 2013-12-18 at 12 31 19 pm](https://f.cloud.github.com/assets/458367/1775685/64d92c0c-680a-11e3-9e01-4d952c9093ea.png)