CCBC-450: Optionally return extended network error codes

This commit mostly removes the mentions of the various CONNECT_ERROR and
NETWORK_ERROR return codes and refers them to a new function,
lcbio_mklcberr which will optionally use more extended detailed network
error codes. This behavior is disabled by default, but may be enabled by
lcb_cntl().

Change-Id: I7420c4bd378ab0ff3239eaaa9411a8d5f3d39f0b
Reviewed-on: http://review.couchbase.org/38297
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>