Fix a problem with empty yaml files

On some installations, YALM.load_file will give the error
Psych::SyntaxError:
control characters are not allowed at line 1 column 1
if the loaded file is entirely empty.
Merge pull request #1080 from jonas054/fix_psych_problem

Fix a problem with empty yaml files
[Fix #1022] Make auto-correct honor Exclude for individual cops
Merge pull request #1081 from jonas054/fix_1022_autocorrect_exclude

[Fix #1022] Make auto-correct honor Exclude for individual cops