Cleanup Net::LDAP::Connection#search arg handling
Skip fixture add if exists

This can happen if a failure prevents this from being cleaned
up properly in the last run.
Include required search base, fix test DN
Document search args with relevant RFC sections
Merge pull request #139 from ruby-ldap/search-connection-cleanup

Net::LDAP::Connection#search cleanup
Merge remote-tracking branch 'origin/master' into search-timeout

Conflicts:
	lib/net/ldap/connection.rb
change search instrumentation field s/limit/size/

matches up with how `time` param works. @mtodd you okay with this?