Added gitignore and Devguide

Development Guidelines.md

@@ -0,0 +1,30 @@
+1.No "using namespace std;"
+
+2.Clearly declare "private" inside of class. For example:
+
+use 
+```c++
+class item{
+    private:
+    int price;
+    public:
+    getPrice();
+}
+```
+
+instead of class
+ 
+```c++
+class item{
+    int price;
+    public:
+    getPrice();
+}
+```
+
+
+3.Declare inheritance type(public, private, protected) when using inheritance.
+
+4.If not finished with code, add a TODO as comments.
+
+5.Add comments to explain what you want to do.