Added lume.reject(), updated tests and README.md

README.md

@@ -173,6 +173,14 @@ an array and retains its original keys.
 lume.filter({1, 2, 3, 4}, function(x) return x % 2 == 0 end) -- Returns {2, 4}
 ```
 
+### lume.reject(t, fn [, retainkeys])
+The opposite of `lume.filter()`: Calls `fn` on each value of `t` table; returns
+a new table with only the values where `fn` returned false. If `retainkeys` is
+true the table is not treated as an array and retains its original keys.
+```lua
+lume.filter({1, 2, 3, 4}, function(x) return x % 2 == 0 end) -- Returns {1, 3}
+```
+
 ### lume.merge(...)
 Returns a new table with all the given tables merged together. If a key exists
 in multiple tables the right-most table's value is used.