Move isLocal from GadgetRepo to Gadget

We don't actually care whether the repository is local, we want
to know if the specific gadget is local, so it makes sense
for the function to be contained there.

Change-Id: Iae38259f3e99886e6fcf9a74c480697a980aa5f9
Declare SpecialGadgets::$par

Change-Id: I46fc7be020b1f1dd0727bc4670953d2165363e3d
SpecialGadgets: wfMessage --> $this->msg

Change-Id: I7d2a07ebdff0643689e34f7ccde3d6a24b0c7f04
SpecialGadgets: $wgScript --> wfScript()

Change-Id: I3e4d7d8dbfa37a2af32c732d2038c4676b14edfd
Merge "Move isLocal from GadgetRepo to Gadget" into RL2
Merge "Declare SpecialGadgets::$par" into RL2
Merge changes I3e4d7d8d,I7d2a07eb into RL2

* changes:
  SpecialGadgets: $wgScript --> wfScript()
  SpecialGadgets: wfMessage --> $this->msg