You have too many colons in your URL:
git+git:://firstname.lastname@example.org # ----^
Just one colon is required:
pip install git+git://email@example.com
or, in editable mode:
pip install -e git+git://firstname.lastname@example.org
Provided you have a Fortran compiler installed that Just Works.
#egg=<projectname> part is optional and only used to test for dependencies before downloading. It lets pip test if the package is already installed without needing to clone the whole repository.