Add lockfile per namespace

Attempt to create a lock file per namespace on initialization before
creating spool file directories. Error out if there is already a lock
file in place (which means the current process is a duplicate)

Update tests to reflect this.

Also updated existing tests to call marquise_shutdown, where applicable,
to cleanup locks from tests.
Add an apt-get update to get updates of the apts
code review formatting, K&R conventions
use int size of pid_t to determine length of pid buffer
Add return code in function doco
Remove superflous documentation
Add lock_dir environment variables to tests

mostly for travis' sake. This particular commit may fail with functions
other than marquise_init, but marquise_init should be successful
Add more environment variables for MARQUISE_LOCK_DIR
more efficent getting of pid_t as a usable int
Test file exists before performing unlink
convert comments to C style
Add success return comments for new functions
More C-Style comments
Capture shutdown errors and return -1, per marquise.h header comments
Add test to confirm lock_path being constructed properly
Merge pull request #24 from anchor/lockfile

Add lockfile per namespace