copywrite headers break build tags in Golang

[dhiaayachi]

Go build tags need to be at the top line of the file to be considered by go compiler.

Right now, running copyright headers in go file with build tags would break the tags as the header will be inserted before the build tags.

The expected result is for copywrite headers to either:

• offer a way to exclude/include files based on build tags
• detect build tags and insert the header after