add .gitignore file
add more capabilities to the importer

add the following capabilities:
- admin page is now found in the 'Network Admin' >> 'Settings' panel
- posts, pages, and links can be altered on a site by specifying the
site's name/slug
- posts and pages can be added, updated, removed, replaced, append to,
prepended to, and updated using a grep statement
- links can be added, updated, removed, replaced, and updated using a
grep statement
- the spreadsheet format has been updated to reflex these new
capabilities