Changed MooTools to jQuery based color picker

Changed MooTools based color picker (MooRainbow) to a jQuery/Bootstrap based colorpicker (miniColors).
You can see an example on http://labs.abeautifulsite.net/jquery-miniColors

#### Control types
MiniColors comes with 3 types of controls: hue (default), saturation, brightness or wheel.
You can select these via the control attribute in the xml tag, like control="wheel".

#### Test instructions:
Add these fields to the settings part of an xml file of some extension, like a module. Then go to that extensions settings in the admin and test the different color fields.
```
<field name="color1" type="color" default="#049cdb" label="Default color field" />
<field name="color2" type="color" default="" label="Empty color field" />
<field name="color3" type="color" default="#46a546" disabled="true" label="Disabled color field" />
<field name="color4" type="color" default="#ffc40d" control="hue" label="Control: Hue (default)" />
<field name="color5" type="color" default="#9d261d" control="saturation" label="Control: Saturation" />
<field name="color6" type="color" default="#f89406" control="brightness" label="Control: Brightness" />
<field name="color7" type="color" default="#7a43b6" control="wheel" label="Control: Wheel" />
```