[#617] Install from source doc updates
[#618] create symlink from docs/CONTRIBUTING.rst to CONTRIBUTING.txt
Merge branch 'master' into 617-source-install-doc
[#617] Build solr index with -r
[#606] Fix no resource error to not me flash message
Pass current user
[#533] Change paster commands docs to follow paster's conventions

In paster's documentation, a required field is shown in UPPER_CASE, and
underscores are used as word separator.
Add a test
[#533] Update paster's documentation and rename its title
[#533] Remove documentation of paster rights and roles.

They don't exist anymore.
[#509] Fix bug in add/remove groups
[#621] Move extras_validation into __before

This fixes an issue where creating a new resource would crash in
validation if there was a custom field (using convert_to/from_extras)
with a name that sorted after extras validation alphabetically. Fixes #621.
[#708] Fix render_markdown() helper function
[#708] Switch over to use markdown_extract() not misc.py
[#708] Fix tests
[#708] Get markdown_extract() to use RE_MD_HTML_TAGS
[#708] Minor refactor
[#727] Clean up imports in core
[#728] Add ckan.tracking_enabled to app_globals

The ckan.tracking_enabled ini file setting was being ignored, so page
view tracking wasn't working. Adding ckan.tracking_enabled to
app_globals makes the setting work again.

Fixes #728
[#729] Handle languages in URLs when updating page view tracking summary

Page view tracking was failing when a language was selected:

1. Put `ckan.tracking_enabled = true` in your ini file
2. Run CKAN, visit a page with a language e.g. `/en/dataset/annakarenina`
3. Run `paster tracking update`. If you look in your db, in the
   `tracking_summary` table there'll be a row with `package_id`
   `~~not~found~~`.
4. Run `paster tracking export tracking.csv`, the exported CSV file will
   say 0 views.

If you visit the page without the language in the URL e.g.
`/dataset/annakarenina` then run the export command again, the view does
get counted.

This commit fixes the SQL used by the `paster tracking update/export`
command to handle URLs with or without languages at the start.

Fixes #729