Trying to upload a CSV should prompt a format error

[matt-bernhardt]

Trying to import a CSV file into the import-games verb results in the following output:

$ trapp import-games nasl_2016_prepped_cropped.csv
Importing games from nasl_2016_prepped_cropped.csv
Traceback (most recent call last):
  File "C:\Python27\Scripts\trapp-script.py", line 9, in <module>
    load_entry_point('trapp==0.3.0a1', 'console_scripts', 'trapp')()
  File "c:\users\mjbernha\documents\github\trapp\trapp\command_line.py", line 288, in main
    verbImport(args)
  File "c:\users\mjbernha\documents\github\trapp\trapp\command_line.py", line 203, in verbImport
    importGames(args.infile)
  File "c:\users\mjbernha\documents\github\trapp\trapp\command_line.py", line 75, in importGames
    importer = ImporterGames(infile, log)
  File "c:\users\mjbernha\documents\github\trapp\trapp\importer.py", line 20, in __init__
    self.source = Spreadsheet(importFile)
  File "c:\users\mjbernha\documents\github\trapp\trapp\spreadsheet.py", line 9, in __init__
    self.data = open_workbook(file)
  File "c:\python27\lib\site-packages\xlrd-0.9.4-py2.7.egg\xlrd\__init__.py", line 441, in open_workbook
    ragged_rows=ragged_rows,
  File "c:\python27\lib\site-packages\xlrd-0.9.4-py2.7.egg\xlrd\book.py", line 91, in open_workbook_xls
    biff_version = bk.getbof(XL_WORKBOOK_GLOBALS)
  File "c:\python27\lib\site-packages\xlrd-0.9.4-py2.7.egg\xlrd\book.py", line 1230, in getbof
    bof_error('Expected BOF record; found %r' % self.mem[savpos:savpos+8])
  File "c:\python27\lib\site-packages\xlrd-0.9.4-py2.7.egg\xlrd\book.py", line 1224, in bof_error
    raise XLRDError('Unsupported format, or corrupt file: ' + msg)
xlrd.biffh.XLRDError: Unsupported format, or corrupt file: Expected BOF record; found 'MatchTim'

Ideally, something in this should advise the user that an XLSX file is needed. Even better, a CSV file could be accepted - but at least a better error message.