Release Homogenize version 2.0.0-alpha.15.
Release Homogenize version 2.0.0-alpha.15.

 * Update `LICENSE` for 2021.
 * Upgrade `reciprocate` to `0.0.5`.
 * Upgrade `ascension` to `3.0.0-alpha.2`.
 * Upgrade `mvcc` to `2.0.0-alpha.3`.
 * Upgrade `advance` to `3.0.0-alpha.9`.
 * Remove `sudo` from `.travis.ci`.

Closes #118.

bigeasy/homogenize,bigeasy/homogenize