Updated event_listener.rst

Updated event_listener.rst to use the new KernelEvent::isMasterRequest method
Added Versionadded directive to event_listener.rst

Added missing Versionadded directive to event_listener.rst
Added KernelEvent::isMasterRequest method reference
Fixed internals.rst syntax
Update .gitignore example

As confirmed by WouterJ on Stack Overflow [1], the example
.gitignore file [2] is not up-to-date.

This commit updates the documentation to reflect the current state
of the .gitignore file that is included in the Symfony Standard
Edition distribution [3].

[1] http://stackoverflow.com/q/23437768/1001110
[2] http://symfony.com/doc/current/cookbook/workflow/new_project_git.html#initial-project-setup
[3] https://github.com/symfony/symfony-standard/blob/master/.gitignore
Update the complete 'Initial Project Setup' paragraph

As proposed by WouterJ in https://github.com/symfony/symfony-docs/pull/3827
this commit rewrites the 'Initial Project Setup' paragraph.

The documentation now describes the recommended way of creating a
new Symfony2 project, using Composer to download the Standard Distribution
+ vendors (instead of downloading the zipped version). As the Standard
Edition already contains a .gitignore, the example is replaced by a
link to the one stored at GitHub. The article also explains which files
are excluded by .gitignore.

The last step (downloading vendor libraries using Composer) is removed
as this is now covered by step 1.
Indent the tip to be on the same level as the list item
Replace numbered list items with #

...so we don't have to renumber them every time we remove/add a new
item.
Small change in the wording

...as suggested by weaverryan.
Replace static version constraint (2.4.4)

...with a smarter one. Using Composer's tilde operator (~), also known
as the next significant release constraint, we instruct composer to use
at least Symfony 2.3, but not 3.0 or higher.
Some refactoring of the article

Shorten the 2nd list item a bit, and move it into a 'Tip' seems to make
more sense.
Small improvement
Remove dash
Update the tip about the global .gitignore
Update routing.rst

Added a note to provide extra guidance when naming routes
Applied comments
Wrong parameters order and wrong naming

Wrong parameters order and wrong naming on "Using Password Encoders" section
Applied comments
minor #3857 Added little bit information about the route name (WouterJ)

This PR was merged into the 2.3 branch.

Discussion
----------

Added little bit information about the route name

This PR replaces #3263

| Q   | A
| --- | ---
| Doc fix? | no
| New docs? | yes
| Applies to | all
| Fixed tickets | -

Commits
-------

90e654b Applied comments
66d60d2 Update routing.rst
minor #3858 Clarified Password Encoders example (WouterJ)

This PR was merged into the 2.3 branch.

Discussion
----------

Clarified Password Encoders example

This replaces #3618

| Q   | A
| --- | ---
| Doc fix? | yes
| New docs? | no
| Applies to | all
| Ficket tickets | -

Commits
-------

02f072a Applied comments
17999cf Wrong parameters order and wrong naming