Add a way to read from a ZIP archive

[Kodiologist]

Consider a file like this one:

https://en.www.inegi.org.mx/contenidos/programas/ccpv/2010/microdatos/iter/ageb_manzana/01_aguascalientes_2010_ageb_manzana_urbana_xls.zip

It's a ZIP with a single member, which is an Excel file. read_xls only seems to accept a path to a file on disk, not the document as a string, nor an unz connection object, nor a shell command that prints the document to standard output. It would be nice to not have to extract the archive member to disk just to read it.

See also https://stackoverflow.com/questions/26763377/reading-an-excel-file-into-an-r-dataframe-from-a-zipped-folder

[jennybc]

Already covered by #278