519 update deployment docs second try

@nigelbabu I think you're probably the best person to review this, because you're doing the package install, and everything needs to be consistent between the package and source installs.

The new docs are built here:

* <http://docs.ckan.org/en/519-update-deployment-docs-second-try/install-from-source.html>
* <http://docs.ckan.org/en/519-update-deployment-docs-second-try/solr-setup.html>
* <http://docs.ckan.org/en/519-update-deployment-docs-second-try/datastore-setup.html>
* <http://docs.ckan.org/en/519-update-deployment-docs-second-try/post-installation.html>
* <http://docs.ckan.org/en/519-update-deployment-docs-second-try/deployment.html>
* <http://docs.ckan.org/en/519-update-deployment-docs-second-try/filestore.html>
* <http://docs.ckan.org/en/519-update-deployment-docs-second-try/test.html>

I've tested these on my dev machine (using the symlinks into homedir tip) and on a fresh Ubuntu 12.04 VM (including deployment).

These files also changed:

* <https://github.com/okfn/ckan/blob/c634a67fee7ff99ecfa71c72490825d57c63b2cd/ckan/config/deployment.ini_tmpl>
* <https://github.com/okfn/ckan/blob/c634a67fee7ff99ecfa71c72490825d57c63b2cd/test-core.ini>

After this is merged into master, I need to merge it into release-v2.0 and re-test. Some things are different between master and 2.0, e.g. test databases and user names. See <https://github.com/okfn/ckan/issues/816>

Todo:

- [x] Integrate <https://github.com/okfn/ckan/pull/814>
- [x] Add postfix install instructions to `deployment.rst`, see <https://github.com/okfn/ckan/pull/821#issuecomment-17005942>
- [x] Integrate <https://github.com/okfn/ckan/pull/807>
- [x] Fix Travis

Questions:

- Is there a better user name than `seanh`?
- I changed `<VirtualHost 0.0.0.0:8080>` to `<VirtualHost 0.0.0.0:80>` in the
  apache sites-available file, because nginx isn't included in the from-source
  deployment instructions. Does the package install include nginx? Can nginx
  setup instructions be added to `deployment.rst`?
- Can files like `apache.wsgi` and the apache sites-available file be shared
  between source and package installs? Maybe add the file in git somewhere,
  and make them both import it

Changes:

- Changed default virtualenv location from `~/pyenv` to `/usr/lib/ckan/default`

- Changed default config files dir to `/etc/ckan/default`

- Added tip for developers in source install docsS symlink `/usr/lib/ckan` and
  `/etc/ckan` to directories in your homedir to install ckan in your homedir

- Changed default database user from `ckanuser` to `ckan_default`

- Changed default database from `ckan_dev` to `ckan_default`

- Changed default datastore database from `datastore` to `datastore_default`

- Changed default datastore database user from `readonlyuser` to `datastore_default`

- Changed default test databases from `ckan_test` and `ckan_test_datastore` to
  `ckan_test` and `datastore_test`

- Changed default `ckan.site_id` from `ckan.net` to `default`

- Disabled file log handler, rely on Apache's log files only (as we do on our
  servers)

- Changed the docs to use restructured text substitutions for things like the
  paths to the virtualenv and config files, database names, etc. instead of
  typing them out each time

- Changed default FileStore storage dir from `/my/path/to/storage/root/directory` to `/var/lib/ckan/default`

- Lots of minor formatting fixes and editing

So now we have:

    virtualenv:        /usr/lib/ckan/default
    development.ini:   /etc/ckan/default/development.ini
    production.ini:    /etc/ckan/default/production.ini
    ckan.site_id:      default
    Database user:     ckan_default
    Database:          ckan_default
    Datastore user:    datastore_default
    Datastore db:      datastore_default
    Test database:     ckan_test
    Test datastore db: datastore_test
    Filestore dir:     /var/lib/ckan/default