Updated installation instructions to use zip archives rather than Git repositories.
Updated installation instructions to use zip archives rather than Git
repositories.

* Pip can install from archives without needing Git to be installed.
  (Unsurprisingly, the Git URLs need Git to be installed in order to
  work.)  This means the updated instructions will work for a wider
  variety of users.
* Updated describing how to specify particular versions as the syntax
  differs between the archive and repository URL cases.
* Added spaces to help wrapping of URLs.

afbarnard/fitamord