Fix 'invalid secret key' libgpgme error for testing keys.
Fix 'invalid secret key' libgpgme error for testing keys.

We can't use expired keypairs, and the old testing keypair had it's master
secret key destroyed, so I created a new testing keypair.

 * CHANGE gnupghome/TESTING.subkeys.sec to a non-expired keypair:

   pub   4096R/3F148C21 2014-04-23
   uid                  TESTING (INSECURE!) <bridges@torproject.org>
   sub   4096R/C9CB1DCD 2014-04-23
   sub   4096R/79DEF4D1 2014-04-23

   sec#  4096R/3F148C21 2014-04-23
   uid                  TESTING (INSECURE!) <bridges@torproject.org>
   ssb   4096R/C9CB1DCD 2014-04-23
   ssb   4096R/79DEF4D1 2014-04-23

pagea/bridgedb,mmaker/bridgedb,mmaker/bridgedb,pagea/bridgedb