Created Sidebar

Changes in Ironstone
Added:
- sidebar
  - sidebar class and id
  - page-wrap
  - sidebar target management
  - transitions for width and margin
  - use of calc instead of auto margin for supporting browsers

Changed:
- small screen value: 910 => 945
- small screen left and right margins: 11.1 => 11.35
- small screen body: 77.8 => 77.3