FastqRecord: added methods equals, hashcode, toString, length

small change for **FastqRecord**: added methods

* equals
* hashcode
* toString
* length()
Using [`Objects#equal`](http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/Objects.html#equal(java.lang.Object, java.lang.Object)) from Guava can make this code a lot cleaner.