jsvn: allow specifying path to underlying Subversion executable in config file

jsvn

@@ -117,6 +117,7 @@ def get_config():
             'use_pager': True,
             'use_color': True,
             'aliases': {},
+            'svn': '',
             }
     pth = os.path.expanduser('~/.jsvn')
     if os.path.exists(pth):
@@ -713,7 +714,7 @@ def main(argv):
     global using_color
 
     config = get_config()
-    realsvn = findInPath('svn')
+    realsvn = config['svn'] if config['svn'] != '' else findInPath('svn')
     out = sys.stdout
     argv = apply_aliases(config, argv)
     using_pager = False