8c6c2c3c92
1. Allow IpPrefixes to be created from strings. In order to do this, factor out the code from LinkAddress which already does this to a small utility class in NetworkUtils. 2. Truncate prefixes on creation, fixing a TODO. 3. Add a toString method. 4. Write a unit test. While I'm at it, make RouteInfoTest pass again, and convert it to use IpPrefix instead of LinkAddress. Change-Id: I5f68f8af8f4aedb25afaee00e05369f01e82a70b