Added a 'gdbremote' python module that adds two commands: start_gdb_log and end_gdb_log.

When this is imported into your lldb using the "command script import /path/to/gdbremote.py"
these new commands are available within LLDB. 'start_gdb_log' will enable logging with 
timestamps for GDB remote packets, and 'stop_gdb_log' will then dump the details and
also a lot of packet timing data. This allows us to accurately track what packets are
taking up the most time when debugging (when using the ProcessGDBRemote debugging plug-in).

Also udpated the comments at the top of the cmdtemplate.py to show how to correctly import
the module from within LLDB.

llvm-svn: 149030