What we're missing ATM is different documentation versions for different application versions. What this change does is that it's:

- finding out what is the current branch (e.g. 1.0.x)
- finding out out what is the name of the main adoc file (e.g. spring-cloud-sleuth)
- pulling the changes from gh-pages after checkout
- finding out what is the list of comma separated whitelisted branches (via the `docs.whitelisted.branches` prop)
- in gh-pages creating a folder with name of the branch  (e.g. /1.0.x)
copying all the docs/target/generated-docs/ to that folder
- if the branch from which we're calling the script is NOT master then we're changing the ${main.adoc}.html to index.html so that it's easier to access the docs (e.g. http://cloud.spring.io/spring-cloud-sleuth/1.0.x/)