Move the repo fetching logic into functions.
Add checking for necessary files.
Move cloned repos to an 'src' directory.
Simplify the logic to loop over LAYERS.
Add 'src' to path in the environment and bblayers.
Change LAYERS format so we can separate bitbake from the meta layers.
Put new metas directory in the ignores.
fetch: Add ability to fast-forward existing bitbake / meta layer git repos.

This is a bit conservative in that we only fast forward and do nothing
if the git repo and the LAYERS file disagree on the branch name.
fetch.sh: Don't pushd/popd unnecessarily for metas dir.
fetch.sh: Quiet down 'git status' when detecting changes in repos.
build.sh: time the build and direct output to a log file.
fetch.sh: Replace pushd/popd with 'cd'.

Better than requiring bash though OE likely already does.
fetch.sh: Fix bad string comparison in test.
fetch.sh: Make directory for metas before trying to 'cd' into it.
fetch.sh: No need to make METAS_DIR twice.
Source /etc/profile to clean env before adding to PATH.

Running the build script multiple times was causing the PATH variable
to have OE paths added multiple times. This is a quick fix for that.
It'll also screw up situations where people have custom stuff done
in their .profile/.bashrc files ... meh.
fetch.sh: Use --progress when cloning git repos.

This works around a bug when cloning slow repos with buildbot.
LAYERS: Replace 'obsolescent' oe-core.git with the proper openembedded-core.git repo.
LAYERS: Remove unnecessary meta-oe.git meta layer.

Was unused. See bblayers.conf.
Merge branch 'master' into selinux

Conflicts:
	.gitignore
	LAYERS
	build.sh
	conf/bblayers.conf