This PR migrates content from CP Streams Dev Guide.

Here is the top-level page:
![image](https://user-images.githubusercontent.com/11722533/33904945-df9cf804-df31-11e7-93aa-52385961522c.png)

Here is a child page:
![image](https://user-images.githubusercontent.com/11722533/33904976-f2eafabe-df31-11e7-918c-fbf95db0f76b.png)

See related: https://github.com/apache/kafka-site/pull/112

Author: Joel Hamill <joel-hamill@users.noreply.github.com>

Reviewers: Guozhang Wang <wangguoz@gmail.com>

Closes #4252 from joel-hamill/20171122-migrate-cp-dev-guide

Author: Manjula K <manjula@kafka-summit.org>
Author: manjuapu <manjula@confluent.io>

Reviewers: Guozhang Wang <wangguoz@gmail.com>

Closes #3950 from manjuapu/customer-logo-stream

Author: manjuapu <manjula@confluent.io>
Author: Manjula K <manjula@kafka-summit.org>

Reviewers: Ewen Cheslack-Postava <ewen@confluent.io>

Closes #3914 from manjuapu/customer-logo-stream

Author: Eno Thereska <eno.thereska@gmail.com>

Reviewers: Damian Guy <damian.guy@gmail.com>

Closes #3730 from enothereska/minor-docs-aggregates

Author: Damian Guy <damian.guy@gmail.com>

Reviewers: Guozhang Wang <wangguoz@gmail.com>, Eno Thereska <eno.thereska@gmail.com>

Closes #3604 from dguy/memory-management-docs

Content and assets for the updated Streams API landing page

Author: Derrick Or <derrickor@gmail.com>

Reviewers: Michael G. Noll <michael@confluent.io>, Guozhang Wang <wangguoz@gmail.com>

Closes #3540 from derrickdoo/streams-landing-page

Author: Damian Guy <damian.guy@gmail.com>

Reviewers: Matthias J. Sax <matthias@confluent.io>, Guozhang Wang <wangguoz@gmail.com>

Closes #3484 from dguy/iq-doc

1. Added an architecture section.
2. Added a configuration / execution sub-section to developer guide.

Minor tweaks and a bunch of missing fixes from `kafka-site` repo.

Author: Guozhang Wang <wangguoz@gmail.com>

Reviewers: Matthias J. Sax <matthias@confluent.io>, Derrick Or <derrickor@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>

Closes #2488 from guozhangwang/KMinor-streams-docs-second-pass

Added figures for topology and table-stream duality; added sections about aggregations; misc code fixes.

Author: Guozhang Wang <wangguoz@gmail.com>

Reviewers: Damian Guy, Sriram Subramanian

Closes #2482 from guozhangwang/KMinor-streams-docs-first-pass

Author: Jason Gustafson <jason@confluent.io>

Reviewers: Ewen Cheslack-Postava <ewen@confluent.io>

Closes #2008 from hachikuji/add-missing-images

…s to multiple source clusters

Author: Gwen Shapira <cshapi@gmail.com>

Reviewers: Ismael Juma

Closes #356 from gwenshap/KAFKA-2449

…art of the code github

Author: Gwen Shapira <cshapi@gmail.com>

Reviewers: Guozhang Wang

Closes #325 from gwenshap/KAFKA-2665