Harmonize filenames for Cisco devices

[michaelklose]

• Changed *.yml to *.yaml
• Converted lowercase names to uppercase
• Corrected some wrong file names

[rsp2k]

Why rename all those file from *.yml to *.yaml?? Both are currently accepted

[michaelklose]

The primary reason for this PR are the lowercase / uppercase file names as this a really bad experience working with them on the terminal when first you get all uppercase files and at the end the lowercase files.
When I had a look at the files I noticed the view .yml files and changed them as well. More than 95% of the files are .yaml. So why not changing them .yml to .yaml and improve the user experience for all of us.