Update to Hadoop 1.1.1.
Update to Hadoop 0.23.6 and 2.0.3-alpha.
Update to Hadoop 0.23.6 and 2.0.3-alpha.
Upgrade Hadoop 1 to Hadoop 1.1.2.
Update from 0.23.6 to 0.23.7.
Update from 0.23.7 to 0.23.8.
Merge branch '3e' into master
Upgrade from Hadoop 1.1.2 to 1.2.1.
Upgrade from Hadoop 0.23.8 to 0.23.10.
Upgrade from Hadoop 2.0.3-alpha to 2.2.0.
Allow different Hadoop versions to be specified.

See https://github.com/tomwhite/hadoop-book/issues/14 and
https://github.com/tomwhite/hadoop-book/issues/15
Allow snippet version overrides to be done by major Hadoop version.
Introduce hadoop.distro parameter to avoid problems with profile activation.