Revert "Hide "Land to hosted git" button for now"

This reverts commit e8e62f82ceaea7c6ef0c60ff1f6a47c08d56d7d1.

Conflicts:
	src/applications/differential/landing/DifferentialLandingToHostedGit.php

Change-Id: I6a37d5d508c5865cc3d724f696f6c5982274229c
Fix 'Exception usage: PHABRICATOR_USER should be defined' during land to hosted git repo

The error appears for me on a git repo hosted over http,
while another user experiences the same problem with a
ssh-served repo:

Change-Id: Id67aad1074c488e642b00b40ad795e68ceef7be1
https://github.com/phacility/phabricator/issues/566

The root cause is the following in phabricator/bin/commit-hook:

  $username = getenv(DiffusionCommitHookEngine::ENV_USER);
  if (!strlen($username)) {
    throw new Exception(
      pht('usage: %s should be defined!', DiffusionCommitHookEngine::ENV_USER));
  }