Add julialang binary search sample (#107)

* Add julialang binary search sample

* Add unit test

01_introduction_to_algorithms/julia/binary_search.jil

@@ -0,0 +1,27 @@
+using Test
+
+function binary_search(arr,item)
+    low = 0
+    high = length(arr)
+
+    while low <= high
+        mid = (low + high) ÷ 2
+        guess = 0
+        try
+            guess = arr[mid]
+        catch
+            return nothing
+        end
+        if guess == item
+            return mid
+        elseif guess > item
+            high = mid - 1
+        else
+            low = mid + 1
+        end
+    end
+end
+
+arr = [1,3,5,7,9]
+@test binary_search(arr,3) == 2
+@test binary_search(arr,-1) == nothing