Redefine ParseURL into ParseURL and ParseAndNormalizeURL in
DispatchLinkFilter.

This delta removes Normalization from ParseURL and puts it in
a new Noramlize method on walker.URL. The ParseAndNormalizeURL
is a convienence method.
Added walker.URL.Clone to DispatchLinkFilter
DispatchLinkFilter added correctURLNormalization.
Merge branch 'master' into DispatchLinkFilter
First tests implemented in DispatchLinkFilter branch.
First commit to have tests passing in DispatchLinkFilter.
correctURLNormalization will add to domain_info if normalization changes
domain.
DispatchLinkFilter branch is passing all tests with this patch.
Reduced the length of correctURLNormalization in DispatchLinkFilter
Comment update to DispatchLinkFilter
Add a flag to enable/disable link filtering in DispatchLinkFilter.
Merge branch 'master' into DispatchLinkFilter

Conflicts:
	cassandra/dispatcher_test.go
Added a proto test for the case when domain is host:port in
DispatchLinkFilter.
Merge pull request #103 from iParadigms/DispatchLinkFilter

Dispatch link filter