Change the default max items and time bound for a checkpoint.
Change the default max items and time bound for a checkpoint.

This changes the number of default max items and time bound for
a checkpoint to more practical values based on testing and
requirements for 1.7.z release. These values are also configurable
at startup or runtime.

Change-Id: Ib2dd7300635f81ca52dc144c62ae270b3685bfd5
Reviewed-on: http://review.membase.org/5065
Tested-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>

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