Rationalize dependencies; fix analysis complaints about used but non-declared dependencies

Do a cleanup pass through our dependency set so downstreamers get good picture of what they need to include looking at pom.

Poking with dependency plugin, found the following issues:

+ hbase-common is missing listing of a bunch of commons libs
+ Some of our classes make use of slf4j for no good reason. zk, thrift, netty, and yammer, use slf4j but no need for us to be in the slf4j managing game... so I undid our use of it and stop its transitive include everywhere.
+ hbase-examples and hbase-it do not declare includes like hbase-client, hbase-protocol, etc.
+ hbase-hadoop1-compat depended on log4j but doesn't use it.
+ hbase-prefix-tree depends on hadoop but does not declare it (uses WritiableUtil and RawComparator – just two imports... uses the Audience annotations which we could just remove but still these two critical includes)
+ hbase-server wasn't declaring its use of commons-*. Also added excludes of transitive include of log4j by zk and yammer. Got rid of slf4j as a dependency.
+ Add declarations for used libs such as httpclient and commons-math to top-level pom.
+ Removed setting versions on hadoop1 and hadoop2 profile for slf4j mess.