Added 'fromString' method to Direction class

The method takes a string corresponding to a direction and returns
the appropriate Direction enumeration entry.
Added 'isOutside' field to the Room class

When the field is set to true, narration about the weather outside
or the time of day will be added to the description.
Initial work on universe file parsing and weather

Added to the universe class is a field that determines whether the
universe should generate and keep track of weather for the universe.

The major addition in this commit is the removal of the old default
universe and the addition of the universe file parsing code. The
server now checks for definitions of rooms and items in a YAML file
before starting the server. The format is described in part in the
"default.universe.yml" file, which is included here.
Removed useless print statement
Removed debugging error in default universe
Server now checks for invalid direction names

The server will stop parsing and print a pretty message when
it reaches an exit in the file with an invalid direction name.
Improved file verification while parsing

Now allows more robust specification of the expected types of
elements of the YAML file. Also added a more explicit error message
when types don't match expected types while parsing.
Fixed bug in universe file parsing code

Fixed a bug where rooms previously referenced but not defined
were reached and the hash map containing references was not
properly updated.
Refined universe construction

The universe object is not created until after parsing all the rooms,
so that the only way to set the universe's spawn room is through the
constructor.
Changed Hashtable use to HashMap
Fixed broken parsing engine, refined some code

The parser now actually resolves exits between rooms as it's
scanning the file.

Also: removed a definition and use of a redunant method, and
replaced it with the existing one.
Updated the default universe
Merge branch 'universe'