Reduce the amount of duplication of code in getset test
Reduce the amount of duplication of code in getset test

Most of the tests had the same logic to initialize the
input document. Move this to a member and initialize it
during test startup.

The append/prepend tests should also be refactored since
they share a lot of code.

Change-Id: I4a3ac04d216d784edbad5a666ee7e11e4d8f0f0b
Reviewed-on: http://review.couchbase.org/71041
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

couchbase/memcached,couchbase/memcached,daverigby/memcached,couchbase/memcached,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/memcached,daverigby/memcached,daverigby/memcached,couchbase/memcached