Server: move query management code into QueryManager

No functional changes yet

Conflicts:
	src/edu/washington/escience/myria/parallel/Server.java
QueryManager: remove unused function, make functions protected if we can
QueueManager: very simple query queue
skip Big*Test, they were not thought out or are broken
BigClusterTest: skip entirely

Even the setup costs are too high
Merge branch 'master' into server-query-queue

Conflicts:
	src/edu/washington/escience/myria/api/encoding/QueryConstruct.java
	src/edu/washington/escience/myria/parallel/Server.java
	systemtest/edu/washington/escience/myria/systemtest/JsonOperatorTests.java
	systemtest/edu/washington/escience/myria/systemtest/SequenceTest.java
SymmetricHashJoin: alternate sides
MyriaConstants: bump maximum number of active queries

it is pretty easy to issue 5 queries at a time via the profiler, so raise the
limit.
QueryFailureTest: fix tests
QueryManager: add logging
Logger: fix format
TestUtils: add skipIfInTravis and requireTravis

JUnit Assume.assumeTrue() will skip a test if the assumption fails

Also use these new functions to simplify the tests we had before.
TestUtils: remove unused code
TestUtils: add helper function to create a subquery that inserts a relation

And use it in at least one place.
SequenceTest/TestUtils: move range to TestUtils
QueryManager: add helper function for query submission
QueryStatusEncoding: make time fields be DateTime instead of String
SystemTestBase: better error messages
Fix automatic serialization of DateTime
QueryQueueTest: test queuing up two queries