CONTENTdm: Replace project client functions with one function

Replace simple and compound project client functions with one functon that
pulls all metadata from the METS file, instead of from the server. Use
element names as column headers and element text for the row values. Prefers
non-DC metadata and falls back to DC metadata.  Adds AIP UUID and file UUID
columns to the end of the CSV.

Convert to use lxml for more powerful searching. Clean up, add docstrings,
simplify.