LP#2051370: have make_release build browser client by default

LP#2051370: have make_release build browser client by default

This patch replace the -c switch (to build the browser client) with
a -C switch to _skip_ building the browser client. Release tarballs
should always have the browser client, so the main reason to use -C
is just to create the initial DB update script.

To test
-------
[1] Apply patch. Verify that make_release now advertises a -C
    switch.
[2] Run make_release without -C; it should build the browser client.
[3] Run make_release with -C; the browser client build should be skipped.

Release-note: [Developer] make_release now builds the browser client by default.

Signed-off-by: Galen Charlton <gmc@equinoxOLI.org>
Signed-off-by: Jane Sandberg <js7389@princeton.edu>