Define body cell `value` as a computed property
Define body cell `value` as a computed property

Deprecated body cell view `getValue()` and `updateValue()` methods.
Value property is now an alias for the corresponding row property.
It is defined on initialization and updated whenever the column
name changes. This change allows the value to be `get` AND `set`.

j-/ember-cli-llama-table,luxbet/ember-cli-llama-table,luxbet/ember-cli-llama-table,j-/ember-cli-llama-table