Two cupid_webpage fixes

[mnlevy1981]

1. Depending on how your environment is configured, you either need to import util or cupid.util (and git_helper or cupid.git_helper); added try / except blocks for both imports
2. Don't update github_pages_dir to a realpath unless it is non-empty (want to keep default behavior of not doing anything if user doesn't specify -g option; I was getting

RuntimeError: When specifying -g/--github-pages-dir, you must also provide -n/--name

even when not specifying -g)

Description of changes:

• Please add an explanation of what your changes do and why you'd like us to include them.

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• Have you followed the guidelines in our Contributor's Guide?
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• Have you successfully tested your changes locally?

[mnlevy1981]

@dabail10 reported this issue, and I was able to recreate it locally. My testing was just to run cupid-diagnostics and cupid-webpage from key_metrics; I didn't try cupid-webpage with the github pages link, or through the CESM Workflow)

[dabail10]

I tested this in my sandbox and it worked.

[samsrabin]

Sorry about that! Approved.

[TeaganKing]

Thanks @mnlevy1981 ! I tested both the -g and regular options, and everything worked as expected (commands were cupid-webpage and cupid-webpage -g ../../../../samr_cupid/land_cupid_publish_test -n landtest13). Sounds like you're also testing in the CESM workflow, so I'll let you double check that one.

[mnlevy1981]

I verified that the CESM Workflow showed the same

RuntimeError: When specifying -g/--github-pages-dir, you must also provide -n/--name

reported in #200, but switching to this branch fixed it.