Added custom exceptions

src/main/kotlin/exception/DbElementInsertionException.kt

@@ -0,0 +1,4 @@
+package codes.kalar.exception
+
+class DbElementInsertionException(message: String? = null, throwable: Throwable? = null ) : Throwable(message, throwable) {
+}

src/main/kotlin/exception/DbElementNotFoundException.kt

@@ -0,0 +1,4 @@
+package codes.kalar.exception
+
+class DbElementNotFoundException(message: String? = null, throwable: Throwable? = null ) : Throwable(message, throwable) {
+}