Provide the ability to do a separate cache-hint for cloning.

Cloning is one of the very problematic places for high-latency IO
as it reads baskets one-at-a-time.  Hence, it makes a lot of sense
to use lazy-download for this case.  *However*, it may not be
desirable to enable lazy-download for all workflows!  Nor may it
be desirable for the workflow layers to enable lazy-download for
all merges (as some sites don't have the disk space).

This patch allows us to selectively turn on lazy-download only for
merge jobs at a given site by editing site-local-config.xml.
Add release notes file.
Merge pull request #5983 from bbockelm/clone-cache-hint-73x

Provide the ability to do a separate cache-hint for cloning.
Merge pull request #5989 from ktf/dummy-pr-to-test-automerging

Add release notes file.
Merge remote branch 'origin/CMSSW_7_3_X' into CMSSW_7_0_X