Merge pull request #15 from twitter/develop

Bump version 0.1.1
Merge branch 'release/0.1.3'
Merge branch 'release/0.1.4'
HyperLogLog refactoring + sparse vector implementation
HLL.initialEstimate should be private
Add cardinality estimation to Bloom filter.
Fix typos.
Add heavy hitters to Count-Min sketch.
Remove leftover print statements.
Add comment.
Merge branch 'release/0.1.5'
cleanup in response to some of oscar's comments; back out Max/Min specialization (will be reintroduced separately)
Semigroup for IndexedSeq
Change size to a lazy val.
Merge pull request #82 from mikegagnon/indexedSeqSemigroup2

Semigroup for IndexedSeq
Merge pull request #73 from echen/add_bf_cardinality

Add cardinality estimation to Bloom filter.
Merge pull request #72 from asiegel34/hyperloglog-refactor

HyperLogLog refactoring + sparse vector implementation
Replace heavyHitterOrder with Ordering.by
Merge remote-tracking branch 'upstream/develop' into add_cms_heavy_hitters
Fix zero for DecayedVector monoid.