Ensure that a call to CachingIterator::rewind() no longer exhausts results up front, which would impose a BufferedIterator design.

Initializing the cache to an empty array also ensures that we can count an empty result set.

On servers before 3.2, the option is ignored, which results in a noticeable delay while running the test suite.

This class was originally added in PHPLIB-112

PHPLIB-284 Highlight API changes in documentation

PHPLIB-53 Add documentation for mapReduce

PHPLIB-288 Document how to specify singleBatch option with Find

PHPLIB-268 Add option maxAwaitTimeMS on getMore commands

Before PHPC 1.2.0, these options could only be specified as query modifiers.

This also updates Travis CI to pull 1.3.0RC1 until a stable 1.3.0 is available.