Created general interface for most algorithms

Created utils methods
Refactored ShellSort

Sorts/SortAlgorithm.java

@@ -0,0 +1,13 @@
+package Sorts;
+
+/**
+ *  The common interface of most algorithms
+ *
+ * @author Podshivalov Nikita (https://github.com/nikitap492)
+ *
+ **/
+public interface SortAlgorithm {
+
+    <T extends Comparable<T>> T[] sort(T[] unsorted);
+
+}