[PPP-3272] - Update all current "infocenter" references to "mind touch"

- Updated link references from infocenter.pentaho.com to help.pentaho.com.
- Tweaked references to InfoCenter to be consistently spelled (casing)
   InfoCenter is how the Doc team wants to refer to the help documentation at this point. No reference to MindTouch since it is only the implementation vehicle.
Merge pull request #428 from rfellows/dev-5.1-LEGACY

[PPP-3272] - Update all current "infocenter" references to "mind touch"