CustomObject asset class added.  

Also added the phpstorm project directory to .gitignore.

Added a class for creating, searching for, and removing Eloqua custom objects.  This is functional as is, but (pending approval from the project owners) I will also be adding a class for interfacing with /data/customObject, so that the data contained in a custom object can be used.

Eloqua docs are at http://topliners.eloqua.com/docs/DOC-3097, although POST is undocumented at this point.
Need an `@test` doxygen declaration here.

- [ ] Done