Update schema version to 2.  Refuse to run with 1.
Update schema version to 2.  Refuse to run with 1.

We've slightly changed the data format and want to have an external
tool update it.

Change-Id: I48d2f412627b7819d7deb34542a8f86de8ce0837
Reviewed-on: http://review.membase.org/4121
Tested-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

couchbaselabs/ep-engine,couchbaselabs/ep-engine,jimwwalker/ep-engine,daverigby/kv_engine,couchbase/ep-engine,teligent-ru/ep-engine,sriganes/ep-engine,owendCB/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,couchbase/ep-engine,couchbaselabs/ep-engine,daverigby/kv_engine,jimwwalker/ep-engine,owendCB/ep-engine,daverigby/ep-engine,jimwwalker/ep-engine,hisundar/ep-engine,abhinavdangeti/ep-engine,jimwwalker/ep-engine,abhinavdangeti/ep-engine,abhinavdangeti/ep-engine,sriganes/ep-engine,owendCB/ep-engine,abhinavdangeti/ep-engine,membase/ep-engine,daverigby/ep-engine,couchbase/ep-engine,sriganes/ep-engine,membase/ep-engine,abhinavdangeti/ep-engine,daverigby/kv_engine,sriganes/ep-engine,daverigby/ep-engine,teligent-ru/ep-engine,membase/ep-engine,zbase/ep-engine,membase/ep-engine,hisundar/ep-engine,owendCB/ep-engine,couchbaselabs/ep-engine,daverigby/kv_engine,zbase/ep-engine,zbase/ep-engine,zbase/ep-engine,hisundar/ep-engine,zbase/ep-engine,hisundar/ep-engine,teligent-ru/ep-engine,couchbaselabs/ep-engine,couchbase/ep-engine