SSE updates, fixes and refactorings.

- Resolved JERSEY-2039: Added support for retry SSE field
- Resolved JERSEY-2073: Fixed broadcaster registration strategy that could lead to new registration rejections caused by false-positive "contains" checks.
- Resolved JERSEY-2073: Introduced SSE EventSource.Builder, EventSource reconnect support + example
- Added reproducer test for JERSEY-2045: Unable to reproduce (see EventOutputTest)
- Other changes:
  - Refactored InboundEvent methods getData(…) -> readData(…)
  - Updated Migration chapter in User guide with a list of breaking changes
  - Updated SSE chapter in User Guide to match SSE API changes
  - Updated SSE API javadoc
  - Cosmetic renames in JerseyTest
  - Fixed wrong copyrights in E2E and integration test project files

Change-Id: I2e66734e306b54c03de3281082d406b98b1a5777
Signed-off-by: Marek Potociar <marek.potociar@oracle.com>