Make commitInsert final in ReadOnlyConnectorMetadata
Allow creating tables in Parquet format
Add AsyncSemaphore
Throttle Presto to a maximum number of concurrent queries
Update provisio and presto-maven-plugins

They were picking up the wrong version of the takari-lifecycle-plugin.
Use absolute references for document links
Add initial connector documentation

Starting documentation for built-in connectors: sys, jmx and tpch.

This is essential information for new Presto users, but it is currently
only available in a smattering of posts on the Presto Google group. This
adds some basic information into the documentation. Each section needs to
be developed, but this is a good starting point.
Bind type as constants and use invokeVirtual to call read/write methods
Store indy method handle bindings in the classloader

Prevously, the were stored in a "callSites" field in every generated class.
This approach has a couple of benefits:
* No need to generate or remember to set the callsites field when the class
is loaded
* No need to use "volatile" for the callsites field
Remove unused method
Cache compiled PagesHashStrategy classes
Generate calls on Type class instead of on concrete subclasses

The generated code may not be able to reference type classes by name if
they are on a different classloader (e.g., plugins)