I made a comment in WuYi's PR that this is not necessary, so WuYi
removed it. Turns out it's necessary after confirming with coreOS
developer.

Pserver etcd registration

evaluator for recurrent group.

Using previous image for travis-ci

Fix bugs for rnn generation.

Because travis-ci has been updated Ubuntu Trusty image, it causes
Paddle CI building error. Just using old image now for hot-fix, I
will add another issue to fix Paddle building in new TravisCI image.

Related link
https://blog.travis-ci.com/2017-06-21-trusty-updates-2017-Q2-launch

Handle multiple processes trying to create the data home directory

Add an order switch to xmap_readers

Rewrite tutorial comments in generic.cmake

ENH: Merge multiple static libs into singe one

Fix unit test error: File exists: '/root/.cache/paddle/dataset'

FIX: Add boost inc dir

Add WITH_GOLANG to control the link of go lib

Allow printer layer to print user-provided message

Move paddle/majel/* to paddle/{platform,framework/*

Make the evaluators inside a recurrent goup true evaluator, meaning that their evaluation results are incorporated into the whole evaluator result.