Use the name as the fallback cache key for vcs packages

Fixes #88

nvchecker/source/vcs.py

@@ -7,12 +7,16 @@ import os.path as _path
 from pkg_resources import parse_version
 import structlog
 
+from . import conf_cacheable_with_name
+
 logger = structlog.get_logger(logger_name=__name__)
 _self_path = _path.dirname(_path.abspath(__file__))
 _cmd_prefix = ['/bin/bash', _path.join(_self_path, 'vcs.sh')]
 
 PROT_VER = 1
 
+get_cacheable_conf = conf_cacheable_with_name('vcs')
+
 def _parse_oldver(oldver):
     if oldver is None:
         return PROT_VER, 0, ''