Fix for #1871, Refactor get_EndParameter -> GetEndParameter

This pull request fixes an issue where geometry conversion was not not done properly in the constructor or geometry extraction methods in ReferencePoint.  

ReferencePoint is unique in RevitNodes in that you can directly supply numeric values for the placement of the Point.  This pull request insures that all of these values are correctly converted on ReferencePoint creation, and correctly converted back from the internal representation in feet when previewed in Dynamo (to meters).

This pull request also replaces all usages of get_EndParameter in RevitNodes with the 2014 version - GetEndParameter.  get_EndParameter does not exist in Revit2015, so many of these conversions were failing.

@ikeough

![curveconversion](https://cloud.githubusercontent.com/assets/916345/3472725/3590ce18-02cf-11e4-8068-58191d7d9b4e.PNG)