Modified the inspector base class to provide a render cycle for classes which extend it
Created a request series inspector which extends the inspector base class
Modified the viewlet manager and inspector base to add a render cycle to simplify the inheritance structure
Created a request series inspector class which extends inspector base and the viewlet manager
Fixed failing tests from the removal of the viewlet support from viewlet manager
Added tests for the request series inspector
Merge pull request #176 from hatched/request-series-inspector

This branch:
- Creates a request series inspector subclass to make it easier to use the inspector.
- Removes viewlet support from the viewlet manager.

__To QA__
- Deploy a charm from the charm browser as normal to make sure that it still works.
- Deploy a local charm and use all interactions in the request-series inspector.
- Upgrade the local charm by dragging the same local charm into the canvas again.