Implement 'import * as' parsing

[dikmax]

See https://github.com/google/closure-templates/blob/master/documentation/reference/file-declarations.md

import * as fooMagic from 'path/to/soy/file/foo.soy';
...
{call fooMagic.button}
  ...
{/call}

Right now there's parsing error on space after import: SoyTokenType.{ expected, got '* as fooMagic.