INSTALL_DIR and RUN_DIR now inherit from BrooklynConfigKeys.BROOKLYN_DATA_DIR which can be set in brooklyn.properties to change the choice of /tmp/brooklyn-alex, giving an easier way to productionise systems (note this was the cause of observed failues where the JS gui got wiped, because it was running under /tmp/brooklyn-xxx/jetty).

INSTALL and RUN support templating (and use that as part of their default), and are republished as sensors so there is a cleaner way to access them.

Also exposing getConfigRaw from entity so callers can detect whether config is actually set, or coming from a default, and tidying up some of the utils.  (Note deprecation cleanups are needed, but will be done as a separate commit.)  This uses a new Maybe (which is like Optional but allowing null and can be overridden with custom error messages) to expose config values without setting default.
tiny fix to Maybe and some of the deprecated getRawConfig methods
Merge branch 'master' into feature/software-children

Conflicts:
	api/src/main/java/brooklyn/entity/Entity.java - just imports
Os routines to delete directories on exit
add ID's to management context, for the individual node and the mgmt plane
cause jetty to use a space unique to the mgmt node so that multiple instances don't clobber each other, and ensure nice cleanup
oops - typo in brooklyn.properties brooklyn.datadir setting
remove usages of things deprecated in this branch
Merge branch 'master' into feature/software-children
work following code review for using brooklyn.datadir in more places
Merge pull request #1153 from ahgittin/feature/software-children

INSTALL_DIR and RUN_DIR now inherit from a nicely configurable BrooklynConfigKeys.BROOKLYN_DATA