Added SystemInfo and FileSystems to query system and file system information, respectively.

src/main/java/net/rubygrapefruit/platform/internal/MutableSystemInfo.java

@@ -0,0 +1,25 @@
+package net.rubygrapefruit.platform.internal;
+
+import net.rubygrapefruit.platform.SystemInfo;
+
+public class MutableSystemInfo implements SystemInfo {
+    public String osName;
+    public String osVersion;
+    public String characterEncoding;
+    public String machineArchitecture;
+
+    @Override
+    public String getKernelName() {
+        return osName;
+    }
+
+    @Override
+    public String getKernelVersion() {
+        return osVersion;
+    }
+
+    @Override
+    public String getMachineArchitecture() {
+        return machineArchitecture;
+    }
+}