waterML 1.1 and 1.0

added explicit classes up to <siteInfo> next is <seriesCatalog>

updated waterml to follow other existing code

changed xml_to_dict to be recursive rather than exhaustive
updated docs for waterml
moved xmlparser back to wml so that namespaces would be localized; updated waterml doc to external cuahsi docs; removed duplicated dict_union
Merge pull request #56 from CowanSM/wml

WaterML 1.0 and 1.1
display credits from CREDITS.txt