This update fixes problem with git not supporting https protocol (which
wasn't affecting cli, but the other repos). The image now has a build of
CURL that supports file:// protocol and so I am removing the workaround
from the Dockerfile.
The new base docker image sets the LD_LIBRARY_PATH to /usr/local/lib
and the yum is not compatible with the special CURL version we build.
This change fixes that by clearing the LD_LIBRARY_PATH for the yum
command invocation.
Replace the base image with an updated one that now contains
clang 3.9 with PGO support and also the new git. So we don't
need to build it here anymore.
