Bump Conduit client version

Summary:
Several related changes:

  - Add a "--conduit-version" flag, so you can actually diff conduit version bumps. Otherwise, the server rejects you.
  - Make "arc upgrade" upgrade both libphutil and arcanist, not just arcanist.
  - Bump the version number to 5. See D2527.

Test Plan:
  - Ran "arc upgrade".
  - Ran "arc diff". Got told there was a version issue.
  - Ran "arc diff --conduit-version=4" to create this diff.

Reviewers: indiefan, nh, vrana, btrahan, jungejason, Makinde

Reviewed By: vrana

CC: aran

Differential Revision: https://secure.phabricator.com/D2528
PHPUnit test engine

Summary:
PHPUnit wrapper for arc.
The idea here is simple - find the test case which is related to the updated
class file. Generate tmp files for json & clover reports, run phpunit
with provided arguments.
It supports phpunit configuration file setting in `.arcconfig`: `phpunit_config`.
Path should be relative to project root.

Test Plan:
- Set `unit_engine` to `PhpunitTestEngine`
- Try running tests with & without `phpunit_config` option.

Reviewers: epriestley, davidreuss

Reviewed By: epriestley

CC: aran, Koolvin, jungejason

Differential Revision: https://secure.phabricator.com/D2472
PHPUnit test name handling improvements

Summary:
Better test name handling for tests with data sets.
Instead of showing test name with full data set, show it's id/name,
e.g. `testConstructor with data set #1`

Test Plan: - Try running tests with data sets

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Koolvin

Differential Revision: https://secure.phabricator.com/D2535
Improve default fill of Differential messages from commits

Summary:
  - When you run "arc diff" in Mercurial, we currently give you an empty template. Instead, prefill a likely template by parsing messages, as we do for Git.
  - Unify Git and Mercurial logic for acquiring messages, since `getLocalCommitInformation()` now provides this information. This should improve Git performance, and allows us to delete some code.
  - Merge messages more intelligently. Currently, we just overwrite fields. Instead, merge arrays (like ccs, reviewers, tasks) and concatenate strings (like summary and test plan). We need to special case "title", see inline.
  - @csilvers: this is a precursor to implementing "--reviewers", etc.

Test Plan: See next post, test plan includes giant output.

Reviewers: btrahan, csilvers, Makinde, jungejason, vrana

Reviewed By: csilvers

CC: aran

Differential Revision: https://secure.phabricator.com/D2536
Add "--reviewers" and "--ccs" flags to arc diff

Summary: Request from @csilvers, whose team is alergic to $EDITOR.

Test Plan:
Adding reviewers and CCs to this diff via CLI. The initial commit message for this diff is:

  Add "--reviewers" and "--ccs" flags to arc diff

  Request from @csilvers, whose team is alergic to $EDITOR.

  Tested: Adding reviewers and CCs to this diff via CLI. The initial commit message for this diff is:
  (...infinite recursion omitted...)

Reviewers: csilvers, btrahan

Reviewed By: csilvers

CC: aran

Differential Revision: https://secure.phabricator.com/D2538
Merge branch 'master' of http://github.com/facebook/arcanist