[FLINK-925] Support KeySelector function returning Tuple types
[FLINK-925] Extended for distinct operator and added test cases

This closes #59
Fix typo in package LICENSE
[Tools] Minor fixes in release script

- Introduced required RELEASE_BRANCH environment variable
- Some hardcoded binary calls (gpg, sha512sum, md5sum) have been
  replaced by environment variables (GPG, SHASUM, MD5SUM) and added
  "" argument for 'sed -i' calls for compatability with OS X
- Removed unused environment variables
- Directly call ssh/scp instead of going through sshpass
Fix typo in CONTRIBUTORS

Fixes a typo in CONTRIBUTORS, replaces tabs by whitespaces for alignment,
and updates email adresses of Apache committers to @apache.org.
Update CONTRIBUTORS file

Updates CONTRIBUTORS file with contributors from 0.6-incubating release
announcement and sorts by first name.
[FLINK-1097] Fixed multiple slf4j bindings when using Hadoop2

I excluded all slf4j-log4j12 transitive dependencies to get rid off the warning that slf4j finds multiple slf4j bindings in the classpath. Additionally, I added log4j-over-slf4j and excluded all log4j transitive dependencies so that slf4j handles also legacy log4j logging messages from dependencies.

Author: Till Rohrmann <trohrmann@apache.org>

Closes #121 from tillrohrmann/FLINK-1097 and squashes the following commits:

b9f76d5 [Till Rohrmann] Excluded slf4j-log4j12 as transitive dependency in order to not have multiple slf4j bindings in the class path. Added log4j-overslf4j and excluded log4j transitive dependencies to collect log4j outputs.
Remove naive verification of tuple size

This verification will not work.
Think of spaces or escaped ?
I think it's easier for users to parse the SQLException

Author: Moritz Schubotz <github@ckurs.de>

Closes #116 from physikerwelt/patch-1 and squashes the following commits:

69a3d2a [Moritz Schubotz] Remove associated test as well
b51b4f0 [Moritz Schubotz] Remove naive verification of tuple size
Remove space after comma for TupleXX.toString()

It is better to save some bytes when writing the output. Users can always overwrite to `toString()` if they want.

Author: Robert Metzger <rmetzger@apache.org>

Closes #118 from rmetzger/benchFixes and squashes the following commits:

cb8a251 [Robert Metzger] Remove space after comma for TupleXX.toString()
Add first functionality to display profiling data in the web interface

* a servlet for providing profiling events
* an html page to profile the events
* an ajax call to load the data from the servlet
[FLINK-964] Draw InstanceSummaryProfilingEvents with flot as line charts (prototype)
[FLINK-964] generalize resource usage JS scripts, style charts
[FLINK-964] tear apart core plotting code and configuration
[FLINK-964] add support for SingleInstanceProfilingEvents (2 versions)
[FLINK-964] Clean-up prototype

* move summary profiling to the dashboard
* keep only one detailed resource usage page (the other page still exists, though)
* allow to modify the displayed time window in the flink-conf.yaml
[FLINK-964] Changes according to code review

* profiling is disable by default
* the plots on the index page and the link to the detailed resource usage page are only shown when profiling is enabled
* remove a backup file