renamed tags command into tag

papers/commands/__init__.py

@@ -8,6 +8,6 @@ import open_cmd
 import edit_cmd
 import remove_cmd
 import websearch_cmd
-import tags_cmd
+import tag_cmd
 import attach_cmd
 import update_cmd

papers/commands/tag_cmd.py

@@ -19,7 +19,7 @@ from ..repo import Repository, InvalidReference
 from . import helpers
 
 def parser(subparsers, config):
-    parser = subparsers.add_parser('tags', help="add, remove and show tags")
+    parser = subparsers.add_parser('tag', help="add, remove and show tags")
     parser.add_argument('referenceOrTag', nargs='?', default = None,
                         help='reference to the paper (citekey or number), or '
                              'tag.')

papers/papers

@@ -20,7 +20,7 @@ cmds = collections.OrderedDict([
         ('remove',      commands.remove_cmd),
         ('open',        commands.open_cmd),
         ('websearch',   commands.websearch_cmd),
-        ('tags', commands.tags_cmd),
+        ('tag',         commands.tag_cmd),
         ('attach',      commands.attach_cmd),
         ('update',      commands.update_cmd),
         ])