Add assertion when comparing Time
Correcting documentation, using default locale.

The documentation was specifying that the Time class was supporting
seconds.
Moving Time constants to CommonsConstants
Format javadoc
New TimeSec class

Extends the Time class and add a seconds field.
Update TimeSec class

Factorize code between Time and TimeSec. These are clonable and you can
switch from a type to another easily.
Update clone method visibility
Update JUnit version to 4.11
Add unit tests for Time class
Correct documentation for sub method in Time
Add methods to TimeSec

Add, sub, equals, hashcode, clone, comparable.