allow usage of `solidarity report` in directories without .solidarity file

[tabrindle]

Currently, solidarity report errors out completely with

tabrindle-mbp:~ tabrindle$ solidarity report
✖ No valid solidarity file was found to report.

when no .solidarity file is available. While I believe it should still print this, printing out the same info we normally do would also be helpful.

[GantMan]

So you mean the header info? And then a friendly message?

[GantMan]

"Hey we didn't find a .solidarity file. SO we reported what we thought, and you can point towards an external file with --solidarityFile './nachos/.solidarity'"

[GantMan]

I'm also gonna add a feature in this PR, when I get to it, to have it look for a solidarity file in a specific node module. Should be epic!