Check in copies of MockWebServer + friends.

This commit includes unmodified copies of MockWebServer and its
supporting classes, taken from
dalvik-dev:libcore/support/src/tests/java.  My test will require some
changes, but I'm committing unchanged versions first so I can more
easily track my changes and eventually merge them back over.

Change-Id: Ic4b79c7a2cbd3bd439864ed94c43fe985eae8e78
3 files changed