Revert "Revert "Build-config""

This reverts commit f9c2de3b57cf02c18821b68b54b2249d9bf07fd7.
remove Build.frigg_tmp_directory()
refactor generation of comments
add Build.load_settings

It loads and parses the content of .frigg.yml in the working
directory
Merge branch 'master' of github.com:tind/frigg into settings-file
add task runner on Build

It will run all tasks in the config file, if something fails it will
report the build as failed and not perform the remaining tasks. Log
files will be concatenated into BuildResult.result_log
add pyyaml to requirements
add .frigg.yml
fix typobugs in the task runner
Merge pull request #9 from relekang/settings-file

Build based on .frigg.yml