ACCUMULO-1785 adds ACCUMULO_VERIFY_ONLY mode to bin/config.sh.

* When set, won't write to local filesystem
 - skips mkdir for ACCUMULO_LOG_DIR
 - skips standalone mode checks
 - skips writing to missing tracers file
* Other behavior changes
 - if GC was set, we won't overwrite it
 - if MONITOR was set, we won't overwrite it

Signed-off-by: Keith Turner <kturner@apache.org>
Merge branch '1.4.5-SNAPSHOT' into 1.5.1-SNAPSHOT

Conflicts:
	bin/config.sh