Gracefully fail LockfileParserError and handle empty lockfiles
update error message that an error occured while reading the lockfile and

not that the file couldn't be read
Merge pull request #687 from RiotGames/lockfile_parser_error-master

Gracefully fail LockfileParserError and handle empty lockfiles
Merge branch 'master' into backport_lockfile_fixes

Conflicts:
	lib/berkshelf/lockfile.rb