Mailgun receive support

Summary:
As you've suggested, I took the SendGrid code and massaged it until it played nice with Mailgun.

btw - unless I'm missing something, it appears that the SendGrid receiver lets you spoof emails (it performs no validation on the data received).

Test Plan: Opened a task with Mailgun. Felt great.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Maniphest Tasks: T4326

Differential Revision: https://secure.phabricator.com/D7989
Add more Subversion unit tests

Summary:
Ref T4327. Adds additional SVN tests to cover:

  - replacing a file with a file;
  - replacing a file with a directory;
  - removing a directory with files in it;
  - adding a directory with files;
  - copying a directory and adding and deleting files inside it.

Test Plan: Ran unit tests. One of these has a slightly irregular parse, see inline.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4327

Differential Revision: https://secure.phabricator.com/D8017
Add even more Subversion unit tests

Summary:
Ref T4327. Adds additional tests:

  - Property changes on the root directory (which has special handling).
  - Copying a file from a previous revision (this is `svn cp svn://server.com/root/some_file@123 some_file`).
  - "Multicopying" a file: this is where a file is copied to several places and moved in the same commit.

Test Plan: Ran unit tests.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4327

Differential Revision: https://secure.phabricator.com/D8018
Add yet more unit tests for Subversion

Summary: Ref T4327. This adds a subpath/partial repository where we import only a subdirectory, and adds tests for it.

Test Plan: Ran unit tests.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4327

Differential Revision: https://secure.phabricator.com/D8019
Verify that SVN repository roots really are repository roots

Summary: Fixes T3238. Ref T4327. Although the instructions are fairly clear on this, it's easy to miss them. Make sure the root the user enters matches the real root.

Test Plan: Added unit tests. Used `bin/repository discover` to hit the check explicitly.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T3238, T4327

Differential Revision: https://secure.phabricator.com/D8020
Improve exception reporting behavior for core exceptions

Summary:
See <https://github.com/facebook/phabricator/issues/487>. If an exception is thrown too high in the stack for the main exception handling to deal with it, we currently never report a stack trace. Instead:

  - Always report a stack trace to the error log.
  - With developer mode, also report a stack trace to the screen.

Test Plan: Added a high-level `throw` and hit both cases. Got traces in the log and traces-under-developer-mode on screen.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D8022
Do not perform write in PhabricatorDaemonLogQuery by default

Summary:
See <http://github.com/facebook/phabricator/issues/487>. By default, we perform a write in this query to moved daemons to "dead" status after a timeout. This is normally reasonable, but after D7964 we do a setup check against the daemons, which means this query is invoked very early in the stack, before we have a write guard.

Since doing this write unconditionally is unnecessarily, surprising, and overly ambitious, make the write conditional and do not attempt to perform it from the setup check.

(We could also move this to a GC/cron sort of thing eventually, maybe -- it's a bit awkward here, but we don't have other infrastructure which is a great fit right now.)

Test Plan: Hit setup issues and daemon pages. Will confirm with user that this fixes things.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D8023
Fix `bin/repository importing` for CLOSEABLE flag

Summary: After adding the CLOSEABLE flag, `bin/repository importing` reports CLOSEABLE commits with no information. Just don't report these, for consistency with the old behavior. Adding flags to show them might be nice at some point if we run into issues where that output would be useful.

Test Plan: Ran `bin/repositroy importing` on a repository with CLOSEABLE commits.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D8024
Homepage sprucing, spacing normalization

Summary: Cleans up the homepage a little bit. Removes the subheaders and buttons, links the panel header, and adds an icon for further hinting. Also aligned things up to the common 16px gutter.

Test Plan: Tested home, differential, and maniphest. Screenshotted changes

Reviewers: epriestley, btrahan

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D8034
Awesomify dragging stuff on workboards

Summary: Such fun. Many pixels. Professional PM. Much Business.

Test Plan: Move stuff in and around workboards

Reviewers: epriestley, btrahan

Reviewed By: btrahan

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D8007