HBASE-18784 if available, query underlying outputstream capabilities where we need hflush/hsync.
* pull things that don't rely on HDFS in hbase-server/FSUtils into hbase-common/CommonFSUtils
* refactor setStoragePolicy so that it can move into hbase-common/CommonFSUtils
* refactor WALProcedureStore so that it handles its own FS interactions
* add a reflection-based lookup of stream capabilities
* call said lookup in places where we make WALs to make sure hflush/hsync is available.
HBASE-19289 Add flag to disable stream capability enforcement
HBASE-19841 Tests against hadoop3 fail with StreamLacksCapabilityException
HBASE-19947 ITU should overwrite HTU local FS
HBASE-20354 better docs for impact of proactively checking hsync support.
* Add to the quickstart guide disabling the hsync check, with a
big warning about how we'll lose data if the check is disabled.
* Add to troubleshooting section so folks searching can get a pointer.