refactor QGCUASParamManager to be Controller-only (no View code)
Fix instance initialization
Fix param widget init
fix one-stage constructor problem
fix rendering of advanced parameters editors
Cleanup buttons in px4config; impl clearing pending list
Merge pull request #334 from tstellanova/mvc_refactor

Refactored QGCUASParamManager so that it is no longer a widget and contains no View code