Add Gin(Go), Jester(Nim)! Now Rust is the fastest!!

This release includes following commits!:tada:

• Change abbreviation for "average" (Thanks @philippgille )
• Run aspnetcore in release mode (Thanks @mattzink )
• Adds Python Flask (Thanks @amscotti )
• Adds Nim's Jester (Thanks @amscotti )
• Adds Go's Gin (Thanks @amscotti )
• Avoid locking ruby / gem versions (Thanks @waghanza )

Sadly, I couldn't run the benchmark tool on Flask server, so it was removed from the results.