Make sure that we work with index descriptors correctly w.r.t. schema

o Take schema read lock
o Use forceGetRecord when using loading schema rules
o Do not verify if a constraint index is online from Cypher
   (they always are and if not due to failure that is detected by kernel)
Change GetOrCreateDocIT to use EmbeddedGraphDatabase

o Also renames "Testbase" to "TestBase" suffix
Add embedded example on how to use Cypher to create unique nodes to manual