Add solution to problem one

A very nice solution if you ask me xD

one.adb

@@ -0,0 +1,55 @@
+--
+--  Project Euler problem #1
+--
+
+with Ada.Containers.Vectors,
+        Ada.Command_Line,
+        Ada.Text_IO;
+
+use Ada.Containers,
+    Ada.Text_IO;
+
+procedure One is
+    package CL renames Ada.Command_Line;
+    package Bucket is new Ada.Containers.Vectors (Index_Type => Natural,
+                                                Element_Type => Natural);
+    --
+    --  Print out multiples of 3 and 5 from 0 to the `Upper`
+    function Multiples (Upper : in Natural) return Bucket.Vector is
+        Numbers : Bucket.Vector;
+    begin
+        -- Non-inclusive
+        for Index in 1 .. (Upper - 1) loop
+            if (Index mod 3) = 0 then
+                Bucket.Append (Numbers, Index);
+            elsif (Index mod 5) = 0 then
+                Bucket.Append (Numbers, Index);
+            end if;
+        end loop;
+        return Numbers;
+    end Multiples;
+begin
+    if CL.Argument_Count < 1 then
+        Put_Line (">>> Insufficient command line parameters!");
+        New_Line;
+        Put_Line ("Please execute with: " & CL.Command_Name & " <maxnumber>");
+        CL.Set_Exit_Status (CL.Failure);
+        return;
+    end if;
+
+    declare
+        Upper_Bound : constant Natural := Natural'Value (Ada.Command_Line.Argument (1));
+        Valid_Numbers : constant Bucket.Vector := Multiples (Upper_Bound);
+        Result : Natural := 0;
+    begin
+        for Index in 0 .. Bucket.Last_Index (Valid_Numbers) loop
+            declare
+                Value : constant Natural := Bucket.Element (Valid_Numbers, Integer (Index));
+            begin
+                Result := (Result + Value);
+            end;
+        end loop;
+
+        Put_Line (Natural'Image (Result));
+    end;
+end One;