New cv upgrade command

[agh1]

Mainly in prep for https://issues.civicrm.org/jira/browse/CRM-19417

[totten]

@agh1 I've added a few small fixes. (Described in commit notes.)

One blocker issue in UpgradeCommand -- the calls to subprocesses pass through data without proper escaping. I suspect they work in typical usage but would break in some scenarios, like if:

• The $problem report includes any single-quotes.
• The $dl['url'] includes any shell characters (eg '&' is common in URLs)
• The user passes in a $reportName or $stability with a shell characters.
• The sys_get_temp_dir() has spaces. (Most Linux systems just use /tmp which is fine, but Win/OSX do funny things.)

Suggestion: all variables passed through to Cv::run() should be escaped with escapeshellarg().

[seancolsen]

When this is merged, it'd be nice to add an answer to this SE question which mentions the new command.

[totten]

@agh1 I've made a few updates on this PR

1. Rebased to match latest master (and force-pushed agh1:cv-upgrade)
2. Significantly revamped the upgrade:db command to support more detailed output. If executed interactively with the default --out=pretty, it will display a lot more info. With -v or -vv, it'll display still more. With -q, it'll be quiet. If executed with a structured format (e.g. --out=json), it should still return the same content.
3. Temporarily disabled the other sub-commands. I think it would be useful to get something merged, and we've set the bar rather high by putting all the commands together. I think it'd be an improvement to get this merged with at least one command. (If nothing else, it'll be easier to maintain the code for all the commands... because they'll show up during grep+refactor cycles.)

[totten]

I did a local build with #2 and #35 and ran the full cv test suite on D7/WordPress/Backdrop, and there don't appear to be any regressions here.

Let's get this merged already!

[totten]

@seanmadsen Posted a comment on https://civicrm.stackexchange.com/a/22949/93 about the cv upgrade:db command.