(TWILL-153) Honor actual resource size of the container

- Determine the -Xmx based on the actual size of the container
  - it can be smaller or bigger than the one requested in the TwillSpec
- Refactor resource specification for AM
  - A forward looking change for TWILL-90
- Simple code cleanup to get rid of code warning from IDE.
- Fix a easy to fail test - ZKClientTest.testExpireRewatch()

This closes #63 in Github

Signed-off-by: Terence Yim <chtyim@apache.org>
18 files changed