Switch all branches to use Dylan's piglit repo.

Piglit commits have a high impact on the test pool, because they
trigger test runs on all associated branches.  Mesa developers are
interested in flagging their own regressions, not the regressions that
occur in piglit.

Change mesa_10.2, mesa_10.3, and jekstrand branches to use a more
stable HEAD than origin/master.  Dylan plans to merge from origin
occasionally.
Fetch remotes before polling branch HEADs.

referencing the HEAD of an unfetched remote will fail.  This happens
the first time branches are polled after. build_specification.xml has
been updated to add a remote.
piglit-build/build.py: Explicitly set build paramters

This explicitly turns on GL, GLES1, GLES2, GLES3, and GLX tests, and
turns of CL tests.

This is a change from the default which does not build GLES tests
builders.py: only try to clean build_dir if it exsits

This fixes a potential bug in the clean() methods.
build_support/__init__.py: Force build, clean, and test order

The order must be clean first, then build, finally test, although steps
may be skipped, they must be run in order. This patch changes a
dictionary to a list of tuples to ensure that an ordered data type is
used.
Add --enable-glx-tls to mesa build

undefined reference to `_glapi_tls_Dispatch' occurs on m32 in certain
situations.  Team recommends --enable-glx-tls to ensure proper linking
with system libs.
Snapshot of jenkins config

The drive is failing on otc-gfxtest-01 jenkins master.  Snapshot all
config so we can recover from the inevitable failure.
make poll_branches more resilient

Occasionally git fetch fails and causes poll_branches to exit.
poll_branches runs in the background and needs to be resilient.
add specific revision option for jenkins builds

when jenkins goes down, we miss revisions.  We need to send builds for
specific revs.
drop dangerous environment settings

Jenkins builds should never be affected by environment variables that
the user may have inadvertantly set.  Drop PKG_CONFIG_PATH,
LD_LIBRARY_PATH, and LIBGL_DRIVERS_PATH before building projects.
Add snbgt2 tester to pool.

Dylan has set up a gt2 sandy bridge for test.  Add it to the build
spec so we can get results for this platform.
add check for environment before deleting key.
add retry of job trigger, in case jenkins is down.
add token to jenkins build params

Now that security is enabled, a password must be provided to start
builds.
add authentication to jenkins config

This commit backs up config changes which turn on authentication.
add output for url error when polling
print output from failed fetch commands
fix concat syntax error