Replace app/bootstrap wildcard with explicit entry

See https://github.com/symfony/symfony-standard/commit/e7b7b0f366465b15a29f44d7ba17287bb0b8392b
Ignore bin folder
Add leading slashes
Keep cache and logs directories
Reorder entries
Rename "Dependencies" section into "Managed by Composer"
Move bootstrap file to "Managed by Composer" section
Rename Composer section
Rename Assets section
Merge pull request #1091 from nicwortel/update-symfony2

Update .gitignore for Symfony2
One more binary type to ignore
Merge pull request #1092 from Arvur/master

One more binary type to ignore
Re-order rules for JetBrains legacy project format

Fixes #1090 - this is the part of that PR that seems justified.
gitignore for Rust
Merge pull request #1095 from Heather/patch-1

New template for Rust
Merge branch 'master' into eclipse_fix