Update README.md

Add a note about where to find custom kernels (to support ad-hoc mode).
Merge pull request #9 from daviddoria/patch-1

Update README.md
Merge pull request #11 from daviddoria/master

Update ManetHelper.java
Update README.md

Explain how to create a JAR file for inclusion in another project.
Update ManetHelper.java

Add a more helpful error message than the stack trace of a null pointer exception.
Merge pull request #12 from daviddoria/patch-2

Update README.md
Merge pull request #13 from daviddoria/patch-3

Update ManetHelper.java