EXP-69. Adds a new example of Scalding syntax to the overview of the express music tutorial.

Reviewed by: juliet
EXP-49. Small fix: importing section of express tutorial.

Reviewed by: juliet
DOC-75: API Working Documentation links broken so removed entire section.
EXP-72. Updates express tutorial to use KijiJob.

Reviewed by: juliet
KIJIMR-176. KijiMR multi-Hadoop version maven docs.

Improve KijiMR's maven setup instructions to specify how to pick
between Hadoop1- and Hadoop2-based builds.