Merge pull request #15 from foobacca/import_export

Add import and export actions
[FIX #16] patched the name of notmuch config file

 * changed name of `.notmuch_config` to `.notmuch-config`, matching the real config file's name given in the doc and as used by notmuch.
Merge remote-tracking branch 'upstream/master' into order_by_count

* upstream/master:
  [FIX #16] patched the name of notmuch config file