equals should not be mandatory in query parameters

before this patch query parameter keys that do not contain an equals are
ignored, i.e. ?key1=one&key2&key3=three would result in key2 not being
present in the parameters Properties. this patch allows such keys to be
added with a default empty string.
Merge pull request #4 from soulseekah/fix-empty-equals

equals should not be mandatory in query parameters