Squashed 'src/dmclock/' changes from d6586d7..64bcc6e

Squashed 'src/dmclock/' changes from d6586d7..64bcc6e

64bcc6e Remove FindGTest and FindBoost, which already exist in cmake required version 2.8.11 and later. Also clean up.
ed6dc60 Do some clean-up and remove memory leaks from tests and simulations.
360172a Allow RunEvery object to be ended before destruction via "join" member function.
135b5d0 Fix two bugs discovered by valgrind. Do some other code clean-up as well.
a26d29e Modify cmake files to match naming of cmake's upstream gtest and ceph's boost.
e23e63f Reorganize CMakeLists.txt files, so that projects that incorporate dmclock can control whether add_test is called. Now, add_test is called only at the top-level. Projects that incorporate dmclock can use add_subdirectory on subdirectories beneath the top-level to selective exactly what is included.

git-subtree-dir: src/dmclock
git-subtree-split: 64bcc6ea697c7e790ec4a4229d1bb1d492f9e803