JERSEY-1716: support Application.getProperties()

- init params were already there
- added handling of context params
- added tests/integration/servlet-3-params module

Change-Id: I5f706130cd54eba2d34de8b4daf9f3977b97b1a1
JERSEY-1541: Empty Reader should be returned from readFrom when no entity is present.

Change-Id: I8c3ab9476651c692cb1a4aadc985cbc407cddd80
Merge "JERSEY-1541: Empty Reader should be returned from readFrom when no entity is present."