revised cbtop commandline parsing
revised cbtop commandline parsing

> also added usage printout

mikewied/cbagent,couchbaselabs/litmus,ronniedada/litmus,pavel-paulau/cbagent,couchbaselabs/priority15,couchbaselabs/priority15,couchbaselabs/priority15,couchbaselabs/litmus,ronniedada/litmus,couchbase/cbmonitor,vmx/cbagent,couchbase/cbmonitor,couchbaselabs/litmus,couchbase/cbagent