Change help text of LCB_INVALID_USERNAME to be more accurate
Change help text of LCB_INVALID_USERNAME to be more accurate

This would otherwise confuse users who are using a usename other than
'Adminsitrator'

Change-Id: I2129cf20eee15a789155035c4277ab3ec4ef8f7e
Reviewed-on: http://review.couchbase.org/43288
Reviewed-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>
Tested-by: Mark Nunberg <e7d42768707bf23038325b0b68d4b577e5f6064a@haskalah.org>

couchbase/libcouchbase,signmotion/libcouchbase,avsej/libcouchbase,mody/libcouchbase,mnunberg/libcouchbase,couchbase/libcouchbase,kojiromike/libcouchbase,maxim-ky/libcouchbase,avsej/libcouchbase,senthilkumaranb/libcouchbase,senthilkumaranb/libcouchbase,mnunberg/libcouchbase,PureSwift/libcouchbase,signmotion/libcouchbase,couchbase/libcouchbase,maxim-ky/libcouchbase,avsej/libcouchbase,kojiromike/libcouchbase,couchbase/libcouchbase,mnunberg/libcouchbase,kojiromike/libcouchbase,signmotion/libcouchbase,avsej/libcouchbase,couchbase/libcouchbase,avsej/libcouchbase,maxim-ky/libcouchbase,couchbase/libcouchbase,couchbase/libcouchbase,mody/libcouchbase,senthilkumaranb/libcouchbase,PureSwift/libcouchbase,mody/libcouchbase,mody/libcouchbase,avsej/libcouchbase,avsej/libcouchbase,maxim-ky/libcouchbase,mnunberg/libcouchbase,signmotion/libcouchbase,senthilkumaranb/libcouchbase,mnunberg/libcouchbase,PureSwift/libcouchbase,PureSwift/libcouchbase,kojiromike/libcouchbase