MB-17508 3/4 Add support for float and boundless ranges for configuration
MB-17508 3/4 Add support for float and boundless ranges for configuration

* Creates a float range validator based on whether the type of the config option
is a float rather than if the validation range is not a rounded number.
* Allows for leaving one of the validation range boundaries unspecified which will
result in the validation in that direction being set to maximum.

Change-Id: I023175cdd9b5ef0b6170c8124fd433eaa0788190
Reviewed-on: http://review.couchbase.org/58938
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>

couchbase/ep-engine,daverigby/kv_engine,daverigby/ep-engine,owendCB/ep-engine,couchbase/ep-engine,hisundar/ep-engine,membase/ep-engine,membase/ep-engine,teligent-ru/ep-engine,membase/ep-engine,daverigby/kv_engine,couchbase/ep-engine,teligent-ru/ep-engine,owendCB/ep-engine,hisundar/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/ep-engine,owendCB/ep-engine,couchbase/ep-engine,owendCB/ep-engine,hisundar/ep-engine,teligent-ru/ep-engine,hisundar/ep-engine,daverigby/ep-engine,membase/ep-engine