Update zend.mail.attachments.rst

Rewrote the whole page since it was just a copy of ZF1 docs with namespaces.
correct some class names
Add documentation for NumberParse filter

Related to zendframework/zf2/#4493 and zendframework/zf2#4510
Update service manager config key for the identity plugin()

'alias' key should be 'aliases'
Fixed validator listing and attaching.
Update for "Using Zend\Navigation in your Album Module"

- line numbers to code examples added
- links to component and view helper added
- small updates for code examples
Updates for "Using Zend\Paginator in your Album Module"

- links to components added
- format for SQL code fixed
Typos fixed
Fix typo in SharedEventManagerInterface path
Fixed incorrect end result being displayed in CamelCaseToX filters
Update zend.cache.storage.adapter.rst

Fixed misspelling
Update zend.validator.regex.rst

Added missing round brackets
Update zend.validator.regex.rst
Update zend.validator.regex.rst
Typo mistake
fixed a typo

the phrase 'for validation' was changed to 'form validation'
Update zend.console.introduction.rst
Updated the Bootstrap file to also include vendor autoloading

I've updated the Bootstrap file so it does check for /vendor/autoload.php and include it if existing, so that Modules installed via composer will be loaded, too.
Merge branch 'patch-1' of https://github.com/stefanotorresi/zf2-documentation into hotfix/#875
Merge branch 'hotfix/#875'

Close #875