Minor bugfixes and test additions in bootstrap module

Fix flag value for the BS_REFRESH_INCR, which should be
a unique bit value (0x08), and not 0x06

Change-Id: I430b964e37d366a38d667f045ed93b88495ae04b
Reviewed-on: http://review.couchbase.org/40161
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>