PHP cookbook: use APC package from pear instead of distro repo

- Because distro-provided APC package sometimes causes PHP to hang
- Use platform_family instead of node['platform']
- Raise NotImplementedError if platform is not supported
update gitlab to 6.7.3

- Update gitlab version: v6.7.3
- Update gitlab shell version: v1.9.1
- Use `remote_file` instead of `file` to fix chef compile error
Merge pull request #180 from phunehehe/gitlab-6.7

update gitlab to 6.7.3
Merge pull request #179 from phunehehe/php-use-latest-apc

PHP cookbook: use APC package from pear instead of distro repo
change variable name to be consistent
add an attribute for wal_keep_segments
default value of archive_timeout is actually 0
wal archiving is not needed for streaming replication (which was why it was put there)
Merge pull request #181 from phunehehe/postgresql

change variable name to be consistent