added s3-fake.js and smoke test.
removed spurious console.log() statements.
Now fake S3 storage is used if CSOL_AWS_FAKE_S3_DIR is specified.

I also added some code that checks to see if the required CSOL_AWS_*
env vars are defined; if they're not, it throws a helpful error and
mentions that CSOL_AWS_FAKE_S3_DIR can be used as an alternative.

Unfortunately I haven't been able to test out this integration yet,
because I'm having trouble figuring out how to upload evidence locally on
the website...
Merge branch 'master' into s3-fake-storage
added docs on CSOL_AWS_FAKE_S3_DIR to readme.