Extend space format definition syntax

In addition to current syntax of space fileds format definition:
 - space:format({{name='field_id', type='integer'}, ...})

Add more ways to define it:
 - space:format({{'field_name', 'integer'}, ...})
 - space:format({{'field_name', type='integer'}, ...})
 - space:format({{'field_name'}, ...})
 - space:format({'field_name', ...})

Fix #2815