Move com_menus modals to Bootstrap

This is a repost of #4562 which was ruined in the rebase...
#### Move modals from mootools to Bootstrap
This is the last (I hope) PR to get all back end using bootstrap modals. The rest are: #4513 #4514 #4561.

Testing:
Apply patch and follow the images below to see where you should focus:
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administrator/index.php?option=com_menus&view=menus
![screenshot 2014-10-12 06 35 39](https://cloud.githubusercontent.com/assets/3889375/4604953/16944584-51c2-11e4-93a2-d6b851a7d117.png)
![screenshot 2014-10-12 06 35 53](https://cloud.githubusercontent.com/assets/3889375/4604954/1d578ac0-51c2-11e4-9552-4d3e1407e0e6.png)
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administrator/index.php?option=com_menus&view=item&layout=edit&id=101
![screenshot 2014-10-12 06 36 12](https://cloud.githubusercontent.com/assets/3889375/4604956/393e0fb6-51c2-11e4-9c80-b481b2051609.png)
![screenshot 2014-10-12 06 36 24](https://cloud.githubusercontent.com/assets/3889375/4604959/4f4465b2-51c2-11e4-968c-0289526c970a.png)

![screenshot 2014-10-12 06 36 36](https://cloud.githubusercontent.com/assets/3889375/4604960/53ad4e48-51c2-11e4-8a97-dac4d0c04482.png)
![screenshot 2014-10-12 06 36 46](https://cloud.githubusercontent.com/assets/3889375/4604961/569be2ae-51c2-11e4-87a5-e4ac6bdf44cf.png)
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