Move handling of varints to a separate class
Place TimestampsIO.Writer.writeVarint method prior to writeZero method
Remove TimestampsIO.Writer.bufferOffset field
Abort if unable to create the timestamps file
Abort when the timestamps file already exists
Add main method to Varint class for debugging purposes.

It reads Varint values from a file and prints them to the console.
Add main method to TimestamperIO for debugging

This replaces the main method on the Varint class
TimestampsIO.main method no longer requires the timeshifts file to exist
Add missing change from previous changeset
Rename TimestampsIO.Writer.writeZeroTo method to writeZerosTo
Move TimestampsIO and Varint classes to an "io" package
Split TimestampsIO into TimestampsReader and TimestampsWriter classes
Remove @since tags from Javadoc
Mark classes as "final"
Move console log parsing out of TimestampsReader.find, into a new class
Make TimestamperOutputStream a top-level class

In order to improve the unit test, TimestamperWriter is now an interface.
Move readAllTimestamps methods into TimestampsIOTest
Define NEWLINE variable in unit tests instead of 0x0A
Drop support for Java 5

- Now requires Jenkins 1.520 or later.
- Add @Override annotations when implementing a method from an interface.
- PowerMockRule no longer works, so remove usages.
- Minor changes to TimestamperConfigTest to suit the newer Jenkins.
Remove dependency on commons-io