Improve installation in docker containers

Lots of minor things:
- Mount the toolset directory so any toolset/* changes are included. Very useful for framework development
- Mount the test directory so any test/* changes are included. Very useful for test development
- Without the above mount changes, you will be rebuild the prerequisites container every time you want to
  change something
- Moved pertest installation directories inside of FWROOT/installs to avoid overwriting when mounting. This
  also seems a lot cleaner, just remove the installs directory to ensure everything is clean
- Delete installs/ directory before building prerequisites container to avoid including a ton of useless context
- Ensure autoremove is run in FWROOT instead of FWROOT/installs (which may not exist per above change)
- Add install-only flag to ensure installation step in docker containers doesn't try to run tests when installing
Run webservers inside docker container

Only tested *go* so far, but it does work as expected.

Setup uses an isolated container per test. Only webservers are inside
docker containers (database and client are both still running on separate hosts).
Passes SSH identity files and results between container and host system invisibly.
Provides live output of container's stdout and stderr to the user's terminal
So far, setup only has to use normal docker containers, not "heavyweight" containers
  that run system services such as syslog. We will see how many tests work inside a
  container as I start testing

Changes:
- Added docker-client flag. You can hackily figure out if you're running inside a container, but this is cleaner
- Modified run_tests to use custom function if --docker or --docker-client flags are used
- Added new run_test method, used when --docker flag is detected

TODO:
 - ensure support for all flags
 - avoid duplicating results parsing
 - testing testing testing