Vendor dependencies

Let's see how I like this workflow.

vendor/users/examples/groups.rs

@@ -0,0 +1,31 @@
+extern crate users;
+use users::{Users, Group, UsersCache, get_user_groups, group_access_list};
+
+extern crate env_logger;
+
+
+fn main() {
+    env_logger::init();
+
+    let cache = UsersCache::new();
+
+    let user = cache.get_user_by_uid(cache.get_current_uid())
+        .expect("No current user?");
+
+    let mut groups: Vec<Group> = get_user_groups(user.name(), user.primary_group_id())
+        .expect("No user groups?");
+
+    groups.sort_by(|a, b| a.gid().cmp(&b.gid()));
+    for group in groups {
+        println!("Group {} has name {}", group.gid(), group.name().to_string_lossy());
+    }
+
+    let mut groups = group_access_list()
+        .expect("Group access list");
+
+    groups.sort_by(|a, b| a.gid().cmp(&b.gid()));
+    println!("\nGroup access list:");
+    for group in groups {
+        println!("Group {} has name {}", group.gid(), group.name().to_string_lossy());
+    }
+}