Drops unique constraints through Cypher
Documentation around constraints in Cypher
Merge pull request #751 from systay/7a015a86adb0a3bc7b65d57d2a6057308ef0714f

Drop unique constraint through Cypher
Merge pull request #753 from systay/constraint-docs

Constraint docs
Docs formatting.
Merge pull request #750 from chrisleishman/multi_test

Allow multiple parsers to be semantically tested.
Adds ability to create/drop uniqueness constraints via GraphDatabaseService

o Adds ConstraintCreator in Schema
o Adds ConstraintDefinition, as well as sub-interfaces for specific
  constraint types.
o Adds createDeferredUniquenessConstraint in BatchInserter
o Refactors IndexCreators to use InternalSchemaActions as well
Added note about requirements for server startup using maven to README.md
Added note about requirements for server startup using maven to README.md
Restructured interaction between TxManager and KernelAPI

o Unified the way commit/rollback works by means of interaction between
  TxManager and TransactionContext.
o Rest transaction context (TransitionalPeriodTransactionMessContainer)
  uses the TransactionContext instead of TxManager for communicating
  commit/rollback.
o Removed lock releasing checks stemming from confusion about the
  interaction between these two
Merge pull request #755 from tinwelint/2.0-txmgr-txcontext

Restructured interaction between TxManager and KernelAPI
Adds the concept of constraint indexes.

Indexes can be marked as constraint indexes (owned by a constraints), and the owning constraint gets stored in the IndexRule.

On startup, constraint indexes that don't have an owning constraint gets removed.
Introduces a work-around for removing orphan ConstraintIndexes in HA.

This needs to be improved since the workaround is to not do it...
Initial PEG parser for Cypher
Update parboiled to 1.1.5

Fixes memoMismatches issues
Add syntax check error handling