Bump version and fold in changes for 0.2.1 release

CHANGELOG

changes/bug_all_backends

changes/bug_fix-deps

changes/bug_fix-pip-install

changes/bug_modifiable_timeout

changes/feature_add-action-validation

changes/feature_add-mac-authentication

changes/feature_add-sqlcipher-api

changes/feature_add-status-to-initscript

changes/feature_blank-server

...feature_change-symmetric-encryption-method-to-aes-256-ctr

changes/feature_encode-all-u1db-data-in-couch-backend

changes/feature_encrypt-storage-key-with-kdf

changes/feature_improve-test-coverage

changes/feature_initscript-enhancements

changes/feature_remove-strict-dependency-on-leap.common

changes/feature_split-soledad-client-and-server

changes/feature_use-raw-sqlcipher-key-with-scrypt-as-kdf

soledad/setup.py

soledad_server/setup.py