Ensure varint ordering
Ensure varint ordering
Added varint decode and lexicographical/numeric ordering.

Summary:
This is the baseline on how I will approach tests for the other encodings (random set of values sorted and checked).

Moves toward a fix for #31

Test Plan: unit tests

Reviewers: spencerkimball, petermattis

Subscribers: team

Differential Revision: http://phabricator.cockroachdb.org/D122
use decoder instead of allocating new byte slice and encoding again
string decode
Added varint decode and lexicographical/numeric ordering.

Summary:
This is the baseline on how I will approach tests for the other encodings (random set of values sorted and checked).

Moves toward a fix for #31

Test Plan: unit tests

Reviewers: petermattis, spencerkimball

Reviewed By: spencerkimball

Subscribers: team

Differential Revision: http://phabricator.cockroachdb.org/D122