Add Material Menu component

• Update SDK lower bound to 2.0.0-dev.3.0, matching Angular.
• Material Auto Suggest Input: Replace ngOnChanges(_) with ngAfterChanges.
• Material Button:
  • Update dense mixin to only apply to non-icon buttons.
  • Add mixins for no hover highlight.
  • Add mixins to set icon button padding.
• Material Chips: Update margin on dense theme.
• Material Fab: Update size mixin.
• Material Input:
  • Use markForChanges on inputs since they are being set by a directive and
    not the template and so change detection doesn't happen automatically.
  • Allow numerical values to be internationalized in number validators.
  • Add option to have a material number input component format its contents on
    blur.
• Material Select:
  • Add mixin to set select item padding.
  • Add mixin to set selected item color.
  • Allow customization of Material Dropdown Select's role.
  • Add mixin for pointer events on Material Dropdown Select Items.
  • Fix baseline alignment of dropdown-button in Firefox.
• Material Tree: Improve latency of MaterialTreeFilter.
• Scoreboard:
  • Fix misalignment on OS X with hl=ja.
  • Selected color input overrides default color value in a selectable
    scoreboard.
• Avoid reliance on dynamic typing to access properties.
• Add @input to number validators.
• Cleanup unneeded preserveWhitespace: false and preserveWhitespace: true
  when components manage spacing around themselves.
• Add Observable utilities.
• Update documentation.