support adding salt to log filename
add salt to temporary easyblock build log filename, move log file to unsalted log after successful build
add missing imports, only add salt to log file name (not path)
Merge pull request #656 from boegel/salted_log_file

add salt to temporary log file name
sync with master after #656 was merged into master branch rather than develop branch
Merge pull request #665 from boegel/sync_master

sync with master after #656 was merged into master branch rather than develop branch