Add persist state and restart grill services

Conflicts:

	grill-server/src/main/java/com/inmobi/grill/server/GrillService.java
	grill-server/src/main/java/com/inmobi/grill/server/GrillServices.java
	grill-server/src/main/resources/grill-default.xml
	grill-server/src/test/resources/grill-site.xml
Add persistence to query service

Conflicts:

	grill-api/src/main/java/com/inmobi/grill/api/GrillConf.java
	grill-api/src/main/java/com/inmobi/grill/api/query/QueryHandle.java
	grill-server-api/src/main/java/com/inmobi/grill/server/api/query/QueryContext.java
	grill-server/src/main/java/com/inmobi/grill/server/GrillServices.java
	grill-server/src/main/java/com/inmobi/grill/server/query/QueryExecutionServiceImpl.java
	grill-server/src/test/java/com/inmobi/grill/server/GrillJerseyTest.java
Merge branch 'develop' of https://github.com/InMobi/grill into restart
Update restartability only for launched queries
Update consistent state filter
Update config.apt
Add separate config for enabling restarts and recover from old state
Add non-null check
Update config doc
Merge pull request #2 from InMobi/restart

Grill server to recover running queries upon restarts