bug(md-slide-toggle): slide toggle should fit to it's content width (#3231)

* bug(md-slide-toggle): slide toggle should fit to it's content width

Fixes #3230

* md-slide-toggle: show each slide toggle on it's own row on demo-app

* fix to slide toggle css (demo)

Author: jefersonestevo

src/demo-app/slide-toggle/slide-toggle-demo.html

@@ -1,4 +1,4 @@
-<div>
+<div class="slide-toggle-example">
 
   <md-slide-toggle color="primary" [(ngModel)]="firstToggle">
     Default Slide Toggle

src/demo-app/slide-toggle/slide-toggle-demo.scss

@@ -0,0 +1,5 @@
+.slide-toggle-example {
+  display: flex;
+  flex-direction: column;
+  align-items: flex-start;
+}

src/lib/slide-toggle/slide-toggle.scss

@@ -15,7 +15,7 @@ $mat-slide-toggle-bar-track-width: $mat-slide-toggle-bar-width - $mat-slide-togg
 
 
 .mat-slide-toggle {
-  display: flex;
+  display: inline-block;
   height: $mat-slide-toggle-height;
 
   margin: $mat-slide-toggle-margin 0;