Respect --skip-lock option for uninstall

- Fixes #2848

Signed-off-by: Dan Ryan <dan@danryan.co>

pipenv/cli/command.py

@@ -253,7 +253,7 @@ def install(
 
 
 @cli.command(short_help="Un-installs a provided package and removes it from Pipfile.")
-@option("--lock", is_flag=True, default=True, help="Lock afterwards.")
+@option("--skip-lock/--lock", is_flag=True, default=False, help="Lock afterwards.")
 @option(
     "--all-dev",
     is_flag=True,
@@ -272,7 +272,7 @@ def install(
 def uninstall(
     ctx,
     state,
-    lock=False,
+    skip_lock=False,
     all_dev=False,
     all=False,
     **kwargs
@@ -286,7 +286,7 @@ def uninstall(
         three=state.three,
         python=state.python,
         system=state.system,
-        lock=lock,
+        lock=not skip_lock,
         all_dev=all_dev,
         all=all,
         keep_outdated=state.installstate.keep_outdated,