Merge with sumodirjo/engineering-blogs

[eevmanu]

Doing a quickly diff with this readme I got as a result the lack of these blogs:

• 9gag
• airbrake
• avant
• backtrace
• banksimple
• betterworks
• branch
• captricity
• close.io
• cloudscaling
• coursera
• crowdbooster
• datafloq
• dataiku
• dchq.io
• elastic
• fastmail
• fluidinfo
• hubblehq
• icehouse
• import.io
• influxdata
• jelastic
• kaggle
• machinalis
• pagerduty
• pagico
• persiscope data
• phyramid
• raintank
• rea group
• reddit
• simulmedia
• smugmug
• starva
• stylight
• tellapart
• udacity
• workshape
• yammer
• zenpayroll

I didn't make the test if each of these blogs respect these guidelines:
For company blogs, make sure that 80% of content is technical (posts about interesting technical challenges, lessons they've learned, etc). No PR, self-promoting posts.
For individual blogs, as long as posts are mostly technical (not as strict with the ratio as the company one), I am happy to add them.

Hope this could help :)

[kaizensoze]

Going to add the following:

Airbrake https://airbrake.io/blog/
Backtrace https://backtrace.io/blog/
Machinalis http://www.machinalis.com/blog/
Periscope Data https://www.periscopedata.com/blog
Raintank https://blog.raintank.io/
REA Group http://rea.tech/engineering/

The rest don't have enough technical posts.

[kaizensoze]

Added.

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