Allow exclude_arch and exclude_os_type in qa-suite yamls

Adding the option:

exclude_arch:

or

exclude_os_type:

in the ceph-qa-suite yaml allows tests to be skipped for certain
types of hardware or distros.

Example:

exclude_arch: armv7l

This will make said test not run on arm machines.

exclude_os_type: rhel

Would make multi-distro tests skip a specific test on RHEL.
Do not run multiple tests (for distros) on baremetal.

Teuthology doesnt care about os_type for baremetal (ATM). This
change makes it so you can run tests that have been switched over
to run on multiple distros (on vms) on baremetal as well as all
non-ubuntu tests will be skiped (to avoid running the same test
multiple times on baremetal.

Signed-off-by: Sandon Van Ness <sandon@inktank.com>
queue: only bootstrap new checkouts

Until we figure out why bootstrap is getting stuck like this:

 9851 pts/7    S      0:03 /home/teuthworker/teuthology-master/virtualenv/bin/python ./teuthology-master/virtualenv/bin/teuthology-worker -v --archive-dir /var/lib/teuthworker/archive --tube plana --log-dir /var/lib/teuthworker/archive/worker_logs
 2075 pts/7    Z      0:00  \_ [git] <defunct>
 2112 pts/7    Z      0:00  \_ [git] <defunct>
 2138 pts/7    Z      0:00  \_ [bootstrap] <defunct>
 9852 pts/7    S      0:03 /home/teuthworker/teuthology-master/virtualenv/bin/python ./teuthology-master/virtualenv/bin/teuthology-worker -v --archive-dir /var/lib/teuthworker/archive --tube plana --log-dir /var/lib/teuthworker/archive/worker_logs
 2153 pts/7    Z      0:00  \_ [git] <defunct>
 2177 pts/7    Z      0:00  \_ [git] <defunct>
 2264 pts/7    Z      0:00  \_ [bootstrap] <defunct>
 9853 pts/7    S      0:03 /home/teuthworker/teuthology-master/virtualenv/bin/python ./teuthology-master/virtualenv/bin/teuthology-worker -v --archive-dir /var/lib/teuthworker/archive --tube plana --log-dir /var/lib/teuthworker/archive/worker_logs
 2141 pts/7    Z      0:00  \_ [git] <defunct>
 2276 pts/7    Z      0:00  \_ [git] <defunct>
 2305 pts/7    Z      0:00  \_ [bootstrap] <defunct>
 9854 pts/7    S      0:03 /home/teuthworker/teuthology-master/virtualenv/bin/python ./teuthology-master/virtualenv/bin/teuthology-worker -v --archive-dir /var/lib/teuthworker/archive --tube plana --log-dir /var/lib/teuthworker/archive/worker_logs
 7448 pts/7    Z      0:00  \_ [git] <defunct>
 7449 pts/7    Z      0:00  \_ [git] <defunct>
 7450 pts/7    Z      0:00  \_ [bootstrap] <defunct>
 7452 pts/7    Z      0:00  \_ [teuthology-resu] <defunct>
 9855 pts/7    S      0:01 /home/teuthworker/teuthology-master/virtualenv/bin/python ./teuthology-master/virtualenv/bin/teuthology-worker -v --archive-dir /var/lib/teuthworker/archive --tube plana --log-dir /var/lib/teuthworker/archive/worker_logs
 7712 pts/7    Z      0:00  \_ [git] <defunct>
 7713 pts/7    Z      0:00  \_ [git] <defunct>
 7714 pts/7    Z      0:00  \_ [bootstrap] <defunct>
 7716 pts/7    Z      0:00  \_ [teuthology-resu] <defunct>
 9856 pts/7    S      0:03 /home/teuthworker/teuthology-master/virtualenv/bin/python ./teuthology-master/virtualenv/bin/teuthology-worker -v --archive-dir /var/lib/teuthworker/archive --tube plana --log-dir /var/lib/teuthworker/archive/worker_logs
 2316 pts/7    Z      0:00  \_ [bootstrap] <defunct>
 9857 pts/7    S      0:03 /home/teuthworker/teuthology-master/virtualenv/bin/python ./teuthology-master/virtualenv/bin/teuthology-worker -v --archive-dir /var/lib/teuthworker/archive --tube plana --log-dir /var/lib/teuthworker/archive/worker_logs
 2340 pts/7    Z      0:00  \_ [bootstrap] <defunct>
 9858 pts/7    S      0:01 /home/teuthworker/teuthology-master/virtualenv/bin/python ./teuthology-master/virtualenv/bin/teuthology-worker -v --archive-dir /var/lib/teuthworker/archive --tube plana --log-dir /var/lib/teuthworker/archive/worker_logs
23188 pts/7    Z      0:00  \_ [bootstrap] <defunct>
 9859 pts/7    S      0:03 /home/teuthworker/teuthology-master/virtualenv/bin/python ./teuthology-master/virtualenv/bin/teuthology-worker -v --archive-dir /var/lib/teuthworker/archive --tube plana --log-dir /var/lib/teuthworker/archive/worker_logs

Signed-off-by: Sage Weil <sage@inktank.com>
suite: only skip on non-vps if os-type is actually defined

If it's not defined, as it is (not) with most of the nightlies,
proceed!

Signed-off-by: Sage Weil <sage@inktank.com>
queue: fetch origin, not branch

Signed-off-by: Sage Weil <sage@inktank.com>