Show 'No running apps' instead of a blank page
Modified the build definition to bring in a newer version of the scala-maven-plugin, and to define a base Scala version for compatibility warnings.
Concludes merge from master
Added additional behavior in EndpointsResource to provide endpoints as text for `/v1/apps/endpoints/{appID}`, depending upon the request's accept encoding header.
- Added examples of JSON versus text accept-encoding for endpoints in the REST doc template.
- Updated the example URI used in the doc template.