Make the compiler more strict.

Make warnings errors, fix some silly generics and cast errors & wrap
some long lines.
Travis is still using Java 1.6.

We can't load a 1.7 compiled JAR into HBase which is running under a
1.6 JVM. Also, we must specify source and target as Maven defaults
these values to 1.5. Additionally, since source is specified
regardless of the value (even if it matches the compiling JDK), we
must specify -bootclasspath to point to rt.jar directly otherwise we
get the following warning:

[WARNING] bootstrap class path not set in conjunction with -source 1.6

You can read about the reasons for this warning here:

https://blogs.oracle.com/darcy/entry/bootclasspath_older_source
Force Travis to use the installed JDK and not the default system JDK.
Make build work when mvn is invoked with java7 compiler.

Note, this technically represents a bug in that our Travis build is
using JDK 7 even though we specifically installed JDK 6.

I think the `JAVA_HOME` is not being set properly. I thought I
corrected that in the previous commit, but maybe the process which
invokes `mvn` is still not seeing the resulting `JAVA_HOME` value.

Regardless, this should fix the build for Phil since he's building
with JDK 7 as well; although, this is definitely not ideal.
Figured out a way to workaround maven's busted argument parsing.

The classpath warnings appear to only occur if you invoke javac
forked, which is not how mvn is being currently configured.
Really force Travis to use the installed JDK.
Enable `-V` for mvn on Travis builds.

This let's us see the JVM version as well as the version of Maven.
Merge pull request #15 from seomoz/phs/make-compiler-strict

Make the compiler more strict.