Add initial SPIFFS library (#627)

* Add initial SPIFFS library

* Fix Deep Sleep Examples

* Missed one example

libraries/SPIFFS/src/SPIFFS.h

@@ -0,0 +1,39 @@
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef _SPIFFS_H_
+#define _SPIFFS_H_
+
+#include "FS.h"
+
+namespace fs
+{
+
+class SPIFFSFS : public FS
+{
+public:
+    SPIFFSFS(FSImplPtr impl);
+    bool begin(bool formatOnFail=false, const char * basePath="/spiffs", uint8_t maxOpenFiles=10);
+    bool format();
+    size_t totalBytes();
+    size_t usedBytes();
+    void end();
+    bool exists(const char* path);
+    bool exists(const String& path);
+};
+
+}
+
+extern fs::SPIFFSFS SPIFFS;
+
+#endif /* _SPIFFS_H_ */