Document SeparatedListAdapter.java

Documented SeparatedListAdapter and updated a new link to the article of separating list adapter.
Merge pull request #1 from hongde88/master

Document SeparatedListAdapter.java. Congratulations!
Merge pull request #6 from 8Mobius8/master

Javadocs on Three Classes
Cleaned up some code and added some javadoc
Merge pull request #7 from katharinebrinker/master

Cleaned up some code and added some javadoc
Merging in commits made by other students in CS 175 course.