Fixes Dancer vs Dancer2 consistency in Plugin.pm

* Line 157 was the main confusion.  "supports only Dancer2 1"
* Changes the other ``Dancer2`` pod/comment references to ``Dancer`` or ``Dancer 2`` as appropriate.

Does this look consistent/correct to the rest of you?
Merge pull request #214 from spazm/patch-1

Fixes Dancer vs Dancer2 inconsistency in Plugin.pm