AlloyUI intro - address review comments
LRDOCS-580 Replace the YUI/AlloyUI vs JQuery performance sidebar with paragraphs describing YUI/AlloyUI's performance features.
LRDOCS-580 Update example code to AlloyUI 2.0.0
LRDOCS-580 Update the build section with the latest instructions for 2.0.x. Reorganize the build section too.
LRDOCS-580 Update image numbers and header IDs
LRDOCS-843: Wordsmithing and formatting
LRDOCS-843: Fix seed file reference
LRDOCS-843: Modify instructions and remaining wordsmithing
Merge pull request #785 from jhinkey/alloyui-chapter-updates

AlloyUI chapter updates