Deal with TODO list

Several things implemented in this pull request (notably small)

 * **Do not hang indefinitely for clients** 3c08d55 - We now use a socket timeout of 5 seconds to kill client connections mid-death (so we'll only reset timeout once we've received the full message)
 * **Use calloc everywhere in buxton** 01558dc - Self explanatory
 * **Verify socket strings are null terminated** 0b31810 - Simply protect ourselves from corruption
 * **Fix segfault in buxton_debug call** - a5c7bb6 - Encountered a segfault when using set-value over the wire, due to the BuxtonString changes

Haven't tackled data consistency as its relating to gdbm_reorganize, need to discuss this as it means reproducing the DB in its entirety on each call, so a way of tracking consistency could be based on DB update count.