Added @ThreadSafe to a bunch of stuff.

src/main/java/net/rubygrapefruit/platform/SystemInfo.java

@@ -3,19 +3,23 @@ package net.rubygrapefruit.platform;
 /**
  * Provides access to some system information. This is a snapshot view and does not change.
  */
+@ThreadSafe
 public interface SystemInfo extends NativeIntegration {
     /**
      * Returns the name of the kernel for the current operating system.
      */
+    @ThreadSafe
     String getKernelName();
 
     /**
      * Returns the version of the kernel for the current operating system.
      */
+    @ThreadSafe
     String getKernelVersion();
 
     /**
      * Returns the machine architecture, as reported by the operating system.
      */
+    @ThreadSafe
     String getMachineArchitecture();
 }