summary: updated build scripts for testing.

.gitignore:
  added files created by new targets.

build.xml:
  removed targets install and reinstall.
  modified target help to depend on android_rules.help and only explain targets defined here.
  updated target javadoc.
  added targets lint-xml, lint-html, and monkey.
  added private target -pre-clean to remove files created by new targets.

tests/AndroidManifest.xml:
  updated note on running the tests.

tests/ant.properties:
  removed test.runner as target test is now overridden.

tests/build.xml:
  removed target test-report as it is now integrated with overridden target test.
  overrode target test to disable deleting coverage.em and use the new test runner.
  overrode target help to depend on android_rules.help and only explain targets defined here.
  added targets javadoc, lint-xml, lint-html, and artifacts.
  added private target -pre-clean to remove files created by new targets.

tests/clean-tests.sh:
  new sh script to run through all the tests.