Coding standards in .install files

Patch for adherence to drupal schema/array coding standards in the .install files. Also a typo fix (dafault => default), removed superfluous 'length' property on 'text' type columns, and shifted one of the long answer tables over to use a 'unique keys' declaration instead of just plain 'keys' (as the former is part of the Schema API spec, but the latter is not).