CXX-74 enable clang support for travis-ci

Signed-off-by: Andrew Morrow <acm@mongodb.com>
CXX-123 force inits at link w/ static archive

force inclusion of translation units with MONGO_INITIAILIZERS when
linking with the static archive by adding magic symbols into relevant
cpp files that are referenced from base/initializer.cpp

This prevents unreferenced initiailizers from getting dropped, which
obviously screws up behavior
CXX-77 Backport relevant server repo changes applied between rc0 and rc1