Pass conduit credentials down to children workflow

Summary:
Calling `arc patch` on a diff that's dependent on a different diff tries to patch the parent first.
To patch the parent a child workflow is created, and a conduit is passed down, but the credentials are not and it is not marked as authenticated.

Then when the child tries to get the commit message for the dependency, it checks isConduitAuthenticated() https://secure.phabricator.com/diffusion/ARC/browse/master/src/workflow/ArcanistPatchWorkflow.php;2c3268f03ed70d3221eb1642bIc99ebb39b12902e$800 and on failure pops up an interactive editor for the commit message.

Instead we just pass down the credentials to the childred and mark them as authenticated, so this is not a problem.

Test Plan: With two diffs where DA2 depends on DA1, run `arc patch --force --nobranch DA2` ... this no longer pops an interactive editor for the commit message for the dependency.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: hach-que, seshness, epriestley, Korvin

Maniphest Tasks: T5986

Differential Revision: https://secure.phabricator.com/D10381
restored --head support

Summary: the call to setHeadCommit() was accidentally placed in a `if ($background) {}` block, which was removed in 54bea94. This adds the removed call.

Test Plan: used --head, worked as expected

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10447
Make some strings in `ArcanistPhutilXHPASTLinter` translatable

Summary: `pht`ize some string in `ArcanistPhutilXHPASTLinter` so that they are translatable.

Test Plan: Not 100% sure that I am doing it right...

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10431
Add some missing function parameter typehints

Summary: Add some missing function parameter typehints to the `ArcanistPhutilXHPASTLinter` class.

Test Plan: Eyeball it.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10430
Add an XHPAST lint rule for empty block statements

Summary: Adds an XHPAST linter rule for empty block statements. Basically, if a block statement is empty then it is much neater if the opening (`{`) and closing (`}`) braces are adjacent. Maybe this is just my own personal preference, in which case we could reduce the default severity to `ArcanistLintSeverity::SEVERITY_DISABLED`.

Test Plan: Wrote unit tests. I had to modify a bunch of existing unit tests accordingly.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10434
Apply some autofix linter rules

Summary: Self-explanatory

Test Plan: Eyeball it.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10453
Fix linting for spacing around default parameter assignment in function/method declaration

Summary: Fix linting for spacing around default parameter assignment in function/method declaration so that `function foo($x = null) {}` is preferred in favor of `function foo($x=null) {}`.

Test Plan: Modified existing unit tests.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10429
Fix a typo

Summary: Self-explanatory.

Test Plan: Eyeball it

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10462
Allow classes/functions from a later version if they are used conditionally

Summary:
Fixes T5299. Currently, linting `src/future/http/HTTPSFuture.php` from rPHU will raise the following error:

```
   Error  (XHP31) Use Of PHP 5.3 Features
    This codebase targets PHP 5.2.3, but `curlfile` was not introduced until
    PHP 5.5.0.

             532       // use this "@" stuff.
             533
             534       if (class_exists('CURLFile')) {
    >>>      535         $file_value = new CURLFile((string)$tmp, $info['mime'], $info['name']);
             536       } else {
             537         $file_value = '@'.(string)$tmp;
             538       }
```

However, since this class is being used conditionally, it //should// be fine and no linter errors should be being raised.

Test Plan: Added a test case.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T5299

Differential Revision: https://secure.phabricator.com/D10132
Merge branch 'master' of github.com:facebook/arcanist