[doc] typo in composer.json example & cleaning

+ remove section 1.4.2 : duplicated instructions for sass
Updated navbar docs
Introduce postInstallMirrorTwitterBootstrap scripts
Merge pull request #570 from esion/patch-1

[doc] typo in composer.json example & cleaning
Update fields.html.twig for better file support by adding file_widget
fixed datepicker javascript, removed some erroneous script tags
missed some other duplicated JS in my last commit
Fix javascript syntax error on date_widget
Merge pull request #576 from maarekj/patch-1

Fix javascript syntax error on date_widget
BS3 changed the class to has-error
[BUGFIX] Update icon markup in form to 3.0
[BUGFIX] Update icon macro markup to 3.0
Merge pull request #581 from MisatoTremor/master

[BUGFIX] Update icon markup in form to 3.0
Merge pull request #580 from nethunter/master

BS3 changed the class to has-error
Remove extra spacing between label and asterisk
Added a Menu Extension to KnpMenuBundle for cleaner generation of Navbars.
Changed mopa_bootstrap_navbar to be a pass-through for knp_menu_render
with bootstrap options.
Merge pull request #582 from lavoiesl/label-asterisk-whitespace

Remove extra spacing between label and asterisk
Split widget_addon to widget_addon_prepend and widget_addon_append. Patch converted from PR #534.
Merge pull request #583 from dragonwize/master

Split widget_addon to widget_addon_prepend and widget_addon_append.
Merge branch 'navbar-factory-extension' of github.com:isometriks/MopaBootstrapBundle into isometriks-navbar-factory-extension