makes github search grep and pipeable

• create a application token with read access
• clone repo
• follow script instructions

bundle

export GITHUB_TOKEN=xxx
# or: git config github.token xxx

# search code:
bin/github-grep 'user:grosser unicorn' | grep 'narrow-it-down' | grep -v 'something good'

# search issues and PR comments:
bin/github-grep 'repo:kubernetes/kubernetes network error' --issues | grep 'narrow-it-down' | grep -v 'something good'

NOTE: there are random 403 errors on the last page of a search (usually empty anyway), contacted github support about that :/