Initial mavenization, including example keystore for signing jars

All tests are passing in maven.  The jar file manifest looks good from what I can tell.  I was able to create an intellij project using the "import maven project" feature, and running tests from within intellij works just fine.

I set the version as "1.0-SNAPSHOT".  I figure when there are official releases, folks will want to branch/tag the source and edit the version accordingly.
Suggest adding the following info:

```
<description>A Java API for high-throughput sequencing data (HTS) formats.</description>
<url>http://picard.sourceforge.net/index.shtml</url>

<scm>
  <connection>scm:git:git@github.com:samtools/htsjdk.git</connection>
  <developerConnection>scm:git:git@github.com:samtools/htsjdk.git</developerConnection>
  <url>git@github.com:samtools/htsjdk.git</url>
</scm>

 <developers>
    <developer>
      <name>Firstname Lastname</name>
      <email>name@broadinstitute.org</email>
      <organization>The Broad Institute</organization>
      <organizationUrl>http://www.broadinstitute.org</organizationUrl>
    </developer>
  </developers>
```
I wouldn't bother to add all the developers to the POM, but it's useful to at least have the main point of contact for the repo there.

What license is HTSJDK licensed under? A quick spot-check found files with MIT license headers; if so, I would include:

```
<licenses>
  <license>
    <name>MIT License</name>
    <url>http://www.opensource.org/licenses/mit-license.php</url>
  </license>
</licenses>
```

I would also add a LICENSE.txt file to the repo on Github.