Add bazel standalone build

Test plan:
- bazel clean --expunge
- bazel build uploadvalidator
- bazel test --nocache_test_results //...
- Deploy plugin to gerrit site
- Verify plugin loads without errors
- Verify plugin functionality
- Run tools/eclipse/project.sh
- Import project in Eclipse and verify classpath contains all
  dependencies

Change-Id: I3743c07bed664737743fc5020ef3853f5b46358f
15 files changed