dynamic max_sequential_skip_in_iterations

Summary:
This is not a critical options. Making it dynamic so that we can remove
more reference to cfd->options()

Test Plan: unit test

Reviewers: yhchiang, sdong, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24957
comments for DynamicCompactionOptions test

Summary: as title

Test Plan: n/a

Reviewers: yhchiang, sdong, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24963
dynamic max_mem_compact_level

Summary: as title

Test Plan: unit test

Reviewers: sdong, yhchiang, rven, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D25347
Remove java build from travis
fix erro during merge

Summary:
as title

Test Plan:
make release
Improve the log in Universal Compaction to include more debug information.

Summary:
Previously, the log for Universal Compaction does not include the current
number of files in case the compaction is triggered by the number of files.
This diff includes the number of files in the log.

Test Plan:
make
Fix uninitialized parameter caused by D24513

Summary: D24513 introduced a bug that a variable is not initialized. It also causes valgrind issue.

Test Plan: Run tests used to fail valgrind and make sure it passes

Reviewers: yhchiang, ljin, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D25569
Travis Fix