Analysis task should look for a git commit based on abridged hashes

Analysis task should look for a git commit based on abridged hashes
https://bugs.webkit.org/show_bug.cgi?id=157877
<rdar://problem/26254374>

Reviewed by Chris Dumez.

Made /privileged-api/associate-commit look for commits using LIKE instead of an exact match.
Associate the commit when there is exactly one match.

* public/include/commit-log-fetcher.php:
(CommitLogFetcher::fetch_between):
* public/include/db.php:
(Database::escape_for_like): Extracted from CommitLogFetcher::fetch_between.
* public/privileged-api/associate-commit.php:
(main): Look for the commits using LIKE. Reject whenever there are multiple commits. We limit the number of
matches to two for performance when the user specifies something that almost thousands of commits: e.g. "1".
* public/v3/pages/analysis-task-page.js:
(AnalysisTaskPage.prototype._associateCommit): Added human friendly error messages for mismatching commits.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@201123 268f45cc-cd09-0410-ab3c-d52691b4dbfc