Adding initial http support when xrd not available

[djw8605]

Adding http, and the tests for it, for when xrootd is not available.

There was a lot of work to make curl behave like cp

[matyasselmeci]

This is totally gonna break if dest_dir has a space in it. I suggest quoting it -- either with re.quote() or pipes.quote().

[matyasselmeci]

Can you add a command-line argument to force HTTP? That would be useful for testing.

[matyasselmeci]

I like this! Let me do some testing...

[matyasselmeci]

Can you print a human-readable success/failure message instead of JSON?

[djw8605]

Shoot, it wasn't suppose to print anything. That was a debug line that snuck in.

If it fails, it should print something. But if it's successful, it should be completely quiet, like cp. This was requested by user support a while ago. The exit code the best indication of success or failure.

[matyasselmeci]

Sure, sounds good.

[matyasselmeci]

$ stashcp /chtc/PUBLIC/matyas/Python-3.6.5.tgz Python-3.6.5.tgz
Run: [ERROR] Operation expired
2018-12-12T14:04:24+0000 root         WARNING  XrdCP from cache failed on root://hcc-stash.unl.edu, pulling from main redirector

I'm seeing this message but the operation was successful so the [ERROR] thing is misleading.

[matyasselmeci]

also, why isn't it getting cached? That was not the first time I ran that same command on that same host...

[djw8605]

I made the non-debug messages more quiet.

stashcp itself doesn't cache anything, it relies on cache it connects to to cache the data.