fix setup and teardown methods

- Only set static variables from LdpTest setup. Setup is only called
  once even when several classes inherit from LdpTest.
- Change setup and tear down method names so we don't accidentally
  override them in subclasses.

See https://github.com/cbeust/testng/issues/313

Fixes #192
Merge pull request #202 from spadgett/master

fix setup and teardown methods