Add support for permissions in the Things API.

This commit introduces the PermissionThing and associated parser. The parser determines the value (grant/revoke) of the permission by looking at the first character of the input string - if it is a minus (-) or caret (^), the value is false (revoke), otherwise it is true (grant). To distinguish permissions from other things, the parser requires a prefix of "perm:".

src/test/java/com/garbagemule/MobArena/things/PermissionThingParserTest.java

@@ -0,0 +1,65 @@
+package com.garbagemule.MobArena.things;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.nullValue;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.mockito.Mockito.mock;
+
+import com.garbagemule.MobArena.MobArena;
+import org.junit.Before;
+import org.junit.Test;
+
+public class PermissionThingParserTest {
+
+    private PermissionThingParser subject;
+
+    @Before
+    public void setup() {
+        MobArena plugin = mock(MobArena.class);
+        subject = new PermissionThingParser(plugin);
+    }
+
+    @Test
+    public void noPrefixNoPerms() {
+        String input = "mobarena.use.join";
+
+        PermissionThing result = subject.parse(input);
+
+        assertThat(result, is(nullValue()));
+    }
+
+    @Test
+    public void grant() {
+        String perm = "mobarena.use.leave";
+        String input = "perm:" + perm;
+
+        PermissionThing result = subject.parse(input);
+
+        assertThat(result.getPermission(), equalTo(perm));
+        assertThat(result.getValue(), equalTo(true));
+    }
+
+    @Test
+    public void denyMinus() {
+        String perm = "mobarena.setup.addarena";
+        String input = "perm:-" + perm;
+
+        PermissionThing result = subject.parse(input);
+
+        assertThat(result.getPermission(), equalTo(perm));
+        assertThat(result.getValue(), equalTo(false));
+    }
+
+    @Test
+    public void denyCaret() {
+        String perm = "mobarena.use.join";
+        String input = "perm:^" + perm;
+
+        PermissionThing result = subject.parse(input);
+
+        assertThat(result.getPermission(), equalTo(perm));
+        assertThat(result.getValue(), equalTo(false));
+    }
+
+}