Doc: Removed the reference to Qt Mobile.

Change-Id: I237967f9bdbe3619f074063ffe496fdf8675dd10
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Update build instructions for Windows.

Use VS2013; remove path to qtrepotools, which only exists
in git checkouts.

Task-number: QTBUG-40421
Change-Id: I6409888920041ca1146ee8025aba7ed8aa9c91ad
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Merge remote-tracking branch 'origin/5.3' into 5.4

Change-Id: Ia398d442fb454e47b342c28084206f4b846188e5