Lower treeStableTimer to three minutes for testing.

This should be in the config file....
server-side scripts; fix up git checkouts; pass environment variables

Note: This set of git scripts works for 0.8.6, but will probably fail
for 0.8.8, when the git poller began checking out a bare repo and
storing refs in a funny directory.

- Add server-side scripts
  - add 'git update-server-info' step so slaves can fetch gitpoller repo
  - merge client-side/server-side, usePTY and no usePTY code
- Restore Kent's 'init' step
  - force the git url to work around el6/Fedora weirdness
- Add ability to pass in environment variables and Properties through
  environment
  - Use for git revision

Misc:
- Restore Kent's original build step comments into buildsteps.sh
0.8.6 GitPoller compatibility tweak
Add umask configuration
update config.yaml.sample for recent changes

- global section, umask parameter
- update git config to follow Kent's original scripts
- change script.tty to usePTY
- lots of notes and descriptions
Update HOW-TO-local-git-repo for new changes.

Still the remaining problem of 0.8.8 refs; see file for details.