Fix DB error when trying to tag a repository
Steps to reproduce: Go to a project settings, add tags, click on save changes
Observed behavior: Error 500
```
PG::Error: ERROR: column "taggings_count" does not exist
LINE 1: UPDATE "tags" SET "taggings_count" = COALESCE("taggings_coun...
```
Ran `rake acts_as_taggable_on_engine:install:migrations`, removed the first
migration that created the `tags` and `taggings` table, and added the rest.
* Closes#1512
* Closes#1550
* Closes https://github.com/gitlabhq/gitlabhq/issues/6867
* Closes https://github.com/gitlabhq/gitlabhq/issues/9194
See merge request !577
Fix Error 500 when searching Wiki pages
If a Wiki page turns up a hit in the search results, an error will occur:
```
Completed 500 Internal Server Error in 836ms
NoMethodError - undefined method `slug' for "test.markdown":String:
app/helpers/wiki_helper.rb:10:in `namespace_project_wiki_path'
app/views/search/results/_wiki_blob.html.haml:4:in `_app_views_search_results__wiki_blob_html_haml___2752621660395393333_70299911622700'
actionview (4.1.9) lib/action_view/template.rb:145:in `block in render'
activesupport (4.1.9) lib/active_support/notifications.rb:161:in `instrument'
actionview (4.1.9) lib/action_view/template.rb:339:in `instrument'
actionview (4.1.9) lib/action_view/template.rb:143:in `render'
```
An unhandled String containing the name of the Wiki page would be provided to the URL path generator. This MR handles that case.
Closes#1547
See merge request !592
Support configurable attachment size in Application Settings page
### What does this MR do?
This MR provides the ability to configure the maximum size of an attachment inside a note. A parameter has been added to the Application Settings page.
### Are there points in the code the reviewer needs to double check?
What should be done with the legacy note attachment validation? I added code to make the validation work with the configurable setting. I could see an issue where an admin lowers the limit from 10 megabytes to 5 megabytes, which could cause an existing model to be invalid.
### Why was this MR needed?
We often have attachments that exceed 10 MB, and it would be nice to be able to override the defaults.
### What are the relevant issue numbers / [Feature requests](http://feedback.gitlab.com/)?
See Issue #1258
### Screenshots
Before:

After:

See merge request !407
Don't allow username to end in period.
The current behavior doesn't do username referencing and mentioning in sentences like "I discussed with with @douwe." since `douwe.` is matched as a username.
Addresses private issue https://dev.gitlab.org/gitlab/gitlabhq/issues/2174.
See merge request !438
Replace commits calendar with contributions calendar
* count opening of issues and merge requests
* dont trigger git repository - use events from database
* count pushes instead of commits for faster and easier counting
* much-much faster since does not affected by repository size
See merge request !420
It is same search like we have at issues page. It allows to quickly
filter merge requests based on title or desription. I copy-pasted some
js code from Issues.js. In future search (filtering) logic should be
refactoed into one class for merge requests and issues