EXP-107. (P1) File moves for package reorganization.

This commit is the first step of this KijiExpress package
reorganization. Only file moves are performed.

Reviewed by: daisy
EXP-107. (P2) Place types in packages for package reorg.

This is the second part of this KijiExpress package reorganization. In
this commit, package declarations are changed to agree with the new
organization.

Reviewed by: daisy
EXP-107. (P3) Changes to imports for KijiExpress package reorg.

This commit is the third part of the KijiExpress package
reorganization. It modifies code, scripts, and the README to agree
with the new package structure.

Reviewed by: daisy