Fill in missing test coverage

[blms]

• Adjust test coverage minimum to 86%
• Address missing coverage (see below)
• Adjust test coverage minimum back to 95%

Coverage report:

Name                             Stmts   Miss  Cover
----------------------------------------------------
neuxml/__init__.py                  16     16     0%
neuxml/catalog.py                   73     10    86%
neuxml/utils/migrate_eulxml.py      53      1    98%
neuxml/xmlmap/__init__.py            0      0   100%
neuxml/xmlmap/cerp.py              208     23    89%
neuxml/xmlmap/core.py              256     18    93%
neuxml/xmlmap/dc.py                 69     15    78%
neuxml/xmlmap/eadmap.py            320      3    99%
neuxml/xmlmap/fields.py            536     50    91%
neuxml/xmlmap/mods.py              187      2    99%
neuxml/xmlmap/premis.py             48      0   100%
neuxml/xmlmap/teimap.py             86      0   100%
neuxml/xpath/__init__.py             0      0   100%
neuxml/xpath/ast.py                177     67    62%
neuxml/xpath/core.py                56     33    41%
neuxml/xpath/lexrules.py            40     36    10%
neuxml/xpath/parserules.py          90     47    48%
----------------------------------------------------
TOTAL                             2215    321    86%