Disable reference generation in preformatted/code blocks
### Summary
If a user adds text in code or preformatted text via Markdown or HTML that contains `#XXX`, the system adds a note that issue `XXX` was mentioned. This is particularly annoying because we often list gdb backtrace dumps into our issues, and many issues get mentioned as a result. For example:
```
(gdb) bt
#0 0x00000000004004c4 in second () at main.cc:6
#1 0x00000000004004d2 in first () at main.cc:11
#2 0x00000000004004dd in main () at main.cc:17
(gdb)
```
### Steps to reproduce
1. In an issue, write the above text using Markdown or HTML tags (e.g. `<code>`, `<pre>`).
2. Observe that [issue 1](https://gitlab.com/gitlab-org/gitlab-ce/issues/1) and [issue 2](https://gitlab.com/gitlab-org/gitlab-ce/issues/2) have a note that says they were mentioned.
### Expected behavior
Everything enclosed in the code blocks should be ignored as references.
### Observed behavior
Issues get referenced unnecessarily.
### Fix
I've made `reference_extractor.rb` strip out HTML and Markdown blocks before processing. I considered running the raw text through the entire Markdown processor, but this seems overkill and perhaps could lead to some unintended side effects.
See merge request !365
Supports four different event types all bundled under the "note" event type:
- comments on a commit
- comments on an issue
- comments on a merge request
- comments on a code snippet
Fix namespace in merge request url building
Changes in 42387b733b now require namespace specification and broke abc69c8905.
There are additional helper functions in c530ca00b0, but this seemed easier not to rely on them.
See merge request !363
Don't leak information about private project existence via Git-over-SSH/HTTP.
Fixes#2040 and https://gitlab.com/gitlab-org/gitlab-ce/issues/343.
Both `Grack::Auth` (used by Git-over-HTTP) and `Api::Internal /allowed` (used by gitlab-shell/Git-over-SSH) now return a generic "Not Found" error when the project exists but the user doesn't have access to it.
See merge request !1578
Fix merge request URL passed to Webhooks
If you look at the data structure passed to Webhooks, you will see:
`"url"=>nil`
I don't think any of the Webhooks or services are using this yet, so right now nothing so far depends upon this value being correct.
See merge request !352
* add git_http_url and git_ssh_url to project web hook
* add visibility_level to project web hook
* add documentation about project visibility_level in API
Robert Speicher
Douwe Maan
Dmitriy Zaporozhets
Dmitriy Zaporozhets
Jacob Vosmaer
Stan Hu
Marin Jankovski
Jeroen van Baarsen
Vinnie Okada
Marcin Kulik
