(TWILL-81) Use user home directory as the base directory to construct default location factory in YarnTwillRunnerService. Also includes the following bug fixes

- Instead of using "/twill", which in many cases there would be no write permission, use user home directory.
- Fix a bug in ServiceMain that, when creating LocationFactory for container to use, it should be created with the application directory URI.
- Use MiniDFSCluster to run YarnTestSuite
- Fix a bug in YarnTestSuite that a directory given to create the location factory was getting deleted after each test run, which would break test when using MiniDFSCluster

Signed-off-by: Terence Yim <terence@continuuity.com>
(TWILL-86) Rename ServiceDiscoveryTest to ServiceDiscoveryTestRun to avoid the test being executed twice, one by itself and one by YarnTestSuite.

Signed-off-by: Terence Yim <terence@continuuity.com>
Explicitly set java version when compiling twill-examples
Merge branch 'fix-java-version' into sync