(#787) Move uuid.js require to proper location

I added the import at the wrong place, for #767
while moving it from leveldb adapter.

Also, the decleration for Pouch.uuids goes to the
correct location, so that `Pouch` is available.

Signed-off-by: Rohan Jain <crodjer@gmail.com>
(#569) Fix failing small UUIDs uniquness test

UUIDs of length 4 are too small for testing uniqness
amongst 1000. Its better to use a slightly longer
string for serving as basic UUID.

Signed-off-by: Rohan Jain <crodjer@gmail.com>