Check bisq.asset.Asset file sorting during CI

[blabno]

(edited by @cbeams):

This PR is to deal with several ordering issues that crept into the file over time. So far we've only been eyeballing sort order during PR review, and we missed a few items, so now is a good time to automate checking the sort order via Travis CI.

[cbeams]

ACK. You'll see a few additional commits I've pushed, @blabno. It's a shame how unpredictable the behavior of sort is across machines. I was never able to figure out LC_COLLATE, LC_CTYPE or LC_ALL values that got everything to work consistently. Bit of a hack in the end grepping out the comments, but it works. Thanks for putting this together.

[cbeams]

@blabno, note that I updated the description of the PR as well. In general, even if you and I have just discussed something in Slack (as we had in this situation), even a one-line description in the PR is good practice. It provides context for the uninitiated, especially those who might come along and do reviews. As time goes by we want to get more and more in the culture / mode where anybody who wants to can do a review. This means that PRs should be as self-contained as they can be, without requiring context from Slack or wherever else.

No big deal—just want to start emphasizing this. Really, just a one liner is fine, whatever you think would help an uninitiated person understand why this PR is being submitted, why now, etc.