Bug 1046743 - Make the job part number regex more generic

Prior to this patch each new job that became multi-part (eg xpcshell-1,
xpcshell-2, ...) would need adding to the regex. Since jobnames were
made more consistent, the generic regex doesn't hit false positives, so
we can use this instead for reduced maintenance.

Is the treeherder equivalent of:
https://hg.mozilla.org/webtools/tbpl/rev/b7a6c5411bd8
Bug 1061284 - Fix resultset ISE
Merge pull request #201 from mozilla/fix-resultset-ISE

Bug 1061284 - Fix resultset ISE
fix bug 1059222 - refresh flat_exclusions on save
Bug 1062228 - Set re.IGNORECASE correctly for the build_type regex

Only the re module function .search() accepts the flags argument, for
the regexobject search() method it actually gets interpreted as the
'pos' parameter, since |re.IGNORECASE == 2|.

With this change we now correctly identify tests run on ASAN builds as
buildtype 'asan'.
Bug 1043741 - Use named groups for buildbot jobstep start/end regex
Bug 1043741 - Add step result to structured log artefact
Merge pull request #198 from mozilla/buildtype

Set re.IGNORECASE correctly for the build_type regex (bug 1062228)
Bug 1061758 - Suppress the job name from Mochitest-OOP symbols too

Treeherder equivalent of:
https://hg.mozilla.org/webtools/tbpl/rev/718d944e6511#l3.13
Bug 1062579 - Ensure get_symbol() cannot return an empty job symbol

In the case where 'n' wasn't found for jobs whose symbol letter was
suppressed (eg: a mochitest job that isn't split into multiple parts),
get_symbol() could have previously returned an empty symbol.
The suppression now only takes place if 'n' was found.
Merge pull request #200 from mozilla/parse-step-result

Add step result to structured log artefact (bug 1043741)
Bug 1062924 - Sync B2G device image build regex with TBPL

Treeherder equivalent of:
https://hg.mozilla.org/webtools/tbpl/rev/d0100807c406
(bug 1058808) admin action to clear pushlog cache;
Merge pull request #202 from mozilla/bug-1058808-clear-repo-cache

(bug 1058808) admin action to clear pushlog cache