Make 2nd challenge more modular by breaking out convert methods

Took the original convert_fahrenheit_to_celsius and
convert_celsius_to_fahrenheit methods and broke out the precision and
printing features from them.  Turn these into two stand alone methods:
make_precise_to_two_decimal_places and print_converted_temperature.
Gained more modularity, but lost the ability to print a more specific
statement, letting the user know what they originally converted from and
to.  Now the printed line just states the converted temp.  This could be
accomplished with a hash being assembled and passed.  Might look into
this later.