Develop examples of data grids using the grid design pattern

[mcking65]

Related to issue #29.

[mcking65]

Integrated initial set of commits into master.
Most recent: commit b050f64

Work in progress; making changes to editable content appearance and ARIA properties.

[mcking65]

@accdc, @a11ydoer, @annabbott, @jnurthen, @MichielBijl, @artofraghu

Bryan, Jemma, Ann, James, Michiel, Raghu,

I would like each of you to please review the
data grid examples page.

Thank you!