Remove ExecutionEngine.execute(AbstractQuery, ...)
Remove ExecutionEngineHelper.parseAndExecute

(replaced with execute)
Split PlanDescription to have a minimal external interface
Add CypherCompiler interface

Moves parts of ExecutionEngine into versioned CypherCompiler
wrappers.
Merge pull request #1289 from cleishm/no_query_execution

Remove ExecutionEngine.execute(AbstractQuery, ...), split Plan Description and add CypherCompiler