create an artifact if missing in :log_append

this should never happen, but it does, and it breaks things further down
the line. still trying to find the source of the issue.
Use CBC instead of CFB mode for AES encryption

Even when using CFB, jruby wants block size of 16 bytes. In order to not
add padding it's easier to use CBC, which should take care of this.
add missing autoloads

no idea which ones are really required nowadays?
Use OpenSSL::Cipher::AES explicitly

For some reason using string does not add padding automatically, which
indicates that it chooses wrong mode.
add more logging to :logs_append for when artifact_id is missing
Merge branch 'master' of github.com:travis-ci/travis-core
move move log aggregation logic to their services
validate presence of artifact_id on parts and add more log output
less noisy debug output in :logs_append
try using Coder.clean! on incoming log parts
try not yielding artifact_ids to_i in :logs_aggregate
Allow to get jobs with given state(s) with find_jobs service
remove special treatment for rails/spree enqueueing, instead make limit.by_owner == -1 mean unlimited enqueueing
Merge branch 'master' of github.com:travis-ci/travis-core
Allow to get jobs with given state(s) with find_jobs service
add log tables
use log tables
Send repo slug and number with job:started event
Merge branch 'sf-log-tables'
Merge branch 'master' of github.com:travis-ci/travis-core