Fix status section out of order problem

mutiple status.go in go/cmd add status section in vt status server
for system monitoring purpose. However, the problem is they use init
function and may cause potential section out of order problem on
status page if there is another place to also add a new section.

The fix is to introduce a pluggable hook in each status.go so that
whenever another place want to add a new section, it could do so by
assign the hook in its init method.
change dbconfigs API to accept specific credentials

1. Add a DBConfigFlag bitmask param to RegisterFlags and
   Init methods
2. Add a return value for RegisterFlags method to indicate
   registered DBConfigFlag
3. Add dbconfigs test
v3 proto: UpdateEqual, and a change in Generate

UpdateEqual plan execution is implemented.
Also, if we use Generate, we need to return the generated
value as the last InsertId.
Added additional logging to split_clone.go so that we can see overlapping shards
Merge pull request #235 from youtube/aaijazi_add_logging_for_vtworkers

Added additional logging to split_clone.go so that we can see overlapping shards
v3 proto: add subquery for delete plans

For owned indexes, we have to know which rows are going
to be deleted so that we can delete the corresponding vindex
entries. So, deletes need to run a subquery to identify
these rows. An empty subquery means that the table does
not own any vindexes.
rename splitsPerShard to splits

Vtgate's SplitsQuery only supports total number of splits
and calculate per shard split number based on it. Therefore,
rename VitessConf and VitessInputFormat to reflect this behavior.
Implement etcd flavor for TopoServer.
Increasing some timeouts in split_diff from 30s to 60s.
Merge pull request #239 from youtube/increase_split_diff_to

Increasing some timeouts in split_diff from 30s to 60s
Minor updates to Java tests

- Remove println in MapReduceIT
- Mark integrityexception test as ignored
Travis and Coveralls integration

Add travis configuration and dependencies script
Split integration test make targets to allow parallel execution in Travis
Add go packages required for coverage upload to Coveralls
Add coveralls and travis badges to README

Travis: Retry make targets to address flaky targets
Skip resharding_bytes integration tests in Travis
Travis: Skip more integration tests due to flakiness

test/keyspace_test.py
test/initial_sharding.py
test/initial_sharding_bytes.py
test/resharding.py

[ci skip]
Travis: Remove huge_integration_test target
Update coveralls badge
Align badge
Merge pull request #237 from yaoshengzhe/fix_mr_shard_param

rename splitsPerShard to splits
v3 proto: delete execution, still need tests
v3 proto: sandbox_test tweaks