fix select: null pointer for non-multiple

The default value for the internal list was "undefined" instead of "[]".
It caused a null pointer when trying to convert the model to the
internal list. Fixed by giving the right default value.
chore changelog: release v0.2.18
fix select: move scope init data

Sometimes the choices or selected directives were registring before the
main directive had time to fully initialize itself. Moving the init in
the controller ensure that it's done before any of the directives call
it.
fix dialog: emergence animation is now stable

Add 100ms timeout before adding classes to fix emergence animation.
Remove useless css properties.
fix tabs: update heading when scope changes

The heading was set only at the load of the tab by the "addTab" method.
So, if the value of the heading changed, it was not updated. By passing
the scope to the "addTab" method, we can now directly use the latest
scope's value. Also, it removes a use of "ng-bind-html".
fix tabs: better scope management in transclude

The scope inside a tab is now the same as the scope in which the tabs
directive is called, using the right value for ng-transclude.
fix file-input: add a display block to filename

This fix hide text when the filename is too long.
fix buttons: disabled style

Raised and fab disabled buttons have grey background color. Flat and
icon disabled colors have nos background color.
chore demo: fix ripple in header and sidebar
fix search filter: cancel button line height
fix text fields: watch input $modelValue

Before, model input was watched with $viewChangeListeners method. But,
the model wasn’t correctly watched when changing it programmatically.
Now, we watch $modelValue and everything works fine.
fix transclude: add array injection

Missing array injection caused error after minification.
Merge pull request #53 from lumapps/fix/file-input

fix file-input: add a display block to filename
refactor list: remove useless variables

Use global size variables instead of specific variables.
feat date picker: add date picker component
chore demo: add date picker link in sidebar
chore demo: moment dependency in installation doc
feat date picker: add label attribute

Add label attribute to specify label on text field.