Updated RequestHandler documentation
Fixes #142. Provides a validation check for ensuring that media item names are unique.
The changes also include consistency to how media controllers persist descriptors through a service implementation.
Merge pull request #316 from pencilblue/story/PB142

Fixes #142. Provides a validation check for ensuring that media item names are unique
Fixes #323. Specify Handler Function and Body Parser
Merge pull request #324 from pencilblue/story/PB323

Fixes #323. Specify Handler Function and Body Parser