ToString Method Name

[Jesse Anderson]

The ToString.of() violates the new transform rules and we need to choose a
new name.

Here is the method for reference:
  /**
   * Returns a {@code PTransform<PCollection, PCollection<String>>} which
transforms each
   * element of the input {@link PCollection} to a {@link String} using the
   * {@link Object#toString} method.
   */
  public static PTransform<PCollection<?>, PCollection<String>> of() {
    return new SimpleToString();
  }

Here are the possibilities we've had so far:

   - elements
   - default
   - simple
   - asString
   - simpleString
   - stringValue
   - toString
   - strings
   - make

I think default shouldn't be used as that's a keyword for Lambdas.

Here is the guide that I think of() is violating (@eugene is that correct?):
Name factory functions so that either the function name is a verb, or
referring to the transform reads like a verb: e.g. MongoDbIO.read(),
Flatten.iterables().

What are everyone's thoughts? I'm thinking going back to elements or make,
strings.

Thanks,

Jesse