snapctl should do url checking and throw a better error

[geauxvirtual]

snapctl should do url checking and throw a formatting error if a user does not input a url in the format snapctl is expecting.

[lynxbat]

This goes back to my ask for SNAP_URL to be SNAP_HOST (server:ip)

[lynxbat]

We should expect the user to write the URL

[mbbroberg]

s/pulse/snap/g

[mbbroberg]

Still no good as of current version.

build/bin/snapctl --url asdfasdf task list
Error getting tasks:
Get asdfasdf/v1/tasks: unsupported protocol scheme ""

[tiffanyfay]

I'll tinker around with this.