IntegerPattern should accept negative number

Important in the factorial exercise so the correct error message is
printed.
Add mailing list link.
Add files for checking hw1.
Stubs for project phase 1.
Start build and spelling example.
Added files for homework 2.
Removed number 6 slots.
Add answers for project phase 2.
Code for step 2 of exercise two for spelling correction.
Code for step 2 of exercise two for spelling correction.
Added files for homework 3.
Remove SNAPSHOT.
Add opennlp sourceforge repo to resolvers.
Add spelling correction code up to bigram model.
Fix help message for Cluster's --features argument

The Cluster app's help message for the --features argument was
previously printing out the possible values for distance functions
rather than the possible values for features.
Added files for checking HW2.
Increase version to 0.3.0
Add stub files for HW4.
Update README, prepare for 0.3.0 release.
Add --output-dispersion (-d) option