Move documentation to docs.rs

• A purely administrative release - no functional changes compared to v0.6.0
• Move all documentation to docs.rs

OpenSSL/Snappy dependencies

• Update to latest rust-openssl (#122; many thanks to @flier)
• Replace native snappy dependency with rust-snappy (#116; again many thanks to @flier)
• Performance improvements by avoiding needless cloning during fetching offsets and API improvements around fetching group offsets (#128; many many thanks to @dead10ck)
• Replace SipHasher with XxHash (#145)
• Added Consumer#subscriptions to inspect the consumed topic-partitions (#137)
• Started maintaining integration tests (#143; kudos to @dead10ck)
• Allow borrowing KafkaClient from Consumer/Producer (#136; contributed by @thijsc)
• Don't send client-id by default; but allow specifying one (#140; contributed by @Morsicus)

Duration instead of i32-millis

• Accept time as a std::time::Duration instead of i32 millis (Closes: #115)

Idle connections

• Prevent communication over idle connections (#102)

Producer#send

• Fix for #113

Consumer/Producer enhancements

• Kafka group offset storage support (#95)
• Allow consumer to read topics/partitions without a group (breaking api change) (#105)
• Support for reading multiple topics through consumer (breaking api change) (#31)
• Type safe required-acks api for sending messages (breaking api change) (#97)
• Consumer#fallback_offset defaults to "latest" now (#106)
• Update dependency on crc 1.3 (#98)
• Properly evaluate compression type for fetched messages (#96)

Dependency update

Update byteorder to 0.5

Allow excluding snappy, gzip, openssl through feature guards

Introduce features to exclude third-party dependencies:

• "snappy" to exclude dependency on the snappy crate
• "gzip" to exclude dependency on the flate2 crate
• "security" to exclude dependency on the openssl crate

Ssl support

• Allow Producer/Consumer/KafkaClient to communicate with brokers via SSL - @Hoverbear

Producer/Consumer extensions

This release only slightly changes the public API of kafka-rust compared to 0.2.0.

• Producer will now dispatch messages with the same key to the same partition.
• One public unsafe method has been dropped from the fetch response structure..
• KafkaClient::fetch_messages guarantees to deliver messages with message.offset >= partition.requested-offset (this guarantee was previously available only through Consumer.)
• KafkaClient::fetch_messages and Consumer will now validate the CRC checksum of fetched messages by default. Since this involves some non-trivial overhead, CRC validation can be turned off.