DOCS-26. Update phonebook tutorial for rc4.

Signed-off-by: Juliet Hougland <juliet@wibidata.com>
Small textual edits.  Feel free to reject the changes you don't like, I know they're subjective.

Signed-off-by: Juliet Hougland <juliet@wibidata.com>
Re-added a version of the test section of TopNextSongs.
Adds a link to create a JIRA issue for docs.
Editing pass over Kiji Music Tutorial.

Signed-off-by: Juliet Hougland <juliet@wibidata.com>
Re-organizes userguide package structure. This doesn't seem to break links.

Signed-off-by: Juliet Hougland <juliet@wibidata.com>
Splits the KijiMR userguide into sections.

 - Adds a section for Job History.
 - The original document remains for now and will be removed in a future commit.

Signed-off-by: Christophe Taton <taton@wibidata.com>
KijiMR user-guide: HFile section