HBASE-22688 [HBCK2] Add filesystem fixup to hbck2 (#10)

HBASE-22688 [HBCK2] Add filesystem fixup to hbck2 (#10)

* HBASE-22688 [HBCK2] Add filesystem fixup to hbck2

Adds a general filesystem check command to the HBCK2 list.
Runs just the offline filesystem checks from the old hbck1
HBaseFsck tool. Checks hfile validity, if references and
hfile links are wholesome, and whether the hbase.version
file is present. Pass '--fix' to do fixup.

Depends on hbck1 HBaseFsck being present in hbck2
(HBASE-22680 adds it so this could go in after it)

Does NOT do regiondir or tabledir fixup or fixing of
orphans in hdfs or plugging holes in hdfs.

A hbase-hbck2/src/main/java/org/apache/hbase/FileSystemFsck.java
 Adds a file to handle filesystem fsck checking and fixing.

M hbase-hbck2/src/main/java/org/apache/hbase/hbck1/HFileCorruptionChecker.java
 Formatting fixes and filling out the MOB report so like the hfile
 report.

Signed-off-by: Sean Busbey <busbey@apache.org>
* Fix checkstyle

* More checkstyle fixes