Update changelog for upcoming 1.2.2 release

[MRG+1] Add docs for some scheduler settings

[MRG+1] TST: Fix duplicated test name.

[MRG+1] Parse robots.txt content as native str

[MRG+1] Ignore explicitly compiled python files.

[MRG+1] Handle relative sitemap URLs in robots.txt

[MRG+1] Fix #396 re-triggered issue

[MRG+1] Print more dependencies versions in "scrapy version" verbose output

The InteractiveShellEmbed class is a singleton
and we need to drop the instance with its clear_instance() method
to rebuild the instance from scratch with fresh environment
for each subsequent Scrapy's shell drop in.

[MRG] DOC Remove "Ubuntu" section from sidebar/ToC

As described in http://www.sphinx-doc.org/en/latest/markup/misc.html#metadata

[MRG+1] Add middleware to template project (closes #2335)

[MRG+1] Document `download_latency` meta key

[MRG+1] LinkExtractor PY3 'unicode' type fix

[MRG+1] Add better messages for when response content isn't text (closes #2264)

[MRG+1] Update conda channel to conda-forge and show conda version badge.

Fixes #2373

This avoids to include compiled files in the templates directory.

Test Slot's heartbeat state before stopping it

Also add a test on state of looping task in LogStats extension

Fixes #2011 and #2362

Document update in "Using Firefox for scraping"

Fix typo in media pipeline docs