optimizers.

skip epsilon_proximity check for the first point s diff can be larger than epsilon_proximity and causes no planning output. (#79)

"reference line" has been moved to data_center in the following PR:
https://github.com/ApolloAuto/apollo_dev/pull/61/files

So we don't need to make this change any more. Just get reference line from
current_frame and populate into trajectory debug info.

This reverts commit 36eaa61e.