Amend FileCacheHash for FIPS compliance by using SHA1 instead of MD5

Author: Ruaidhri Primrose

src/React.Core/FileCacheHash.cs

@@ -24,9 +24,9 @@ public class FileCacheHash : IFileCacheHash
 		private const string HASH_PREFIX = "// @hash v3-";
 
 		/// <summary>
-		/// Althorithm for calculating file hashes
+		/// Algorithm for calculating file hashes
 		/// </summary>
-		private readonly HashAlgorithm _hash = MD5.Create();
+		private readonly HashAlgorithm _hash = SHA1.Create("System.Security.Cryptography.SHA1Cng");
 
 		/// <summary>
 		/// Calculates a hash for the specified input

src/React.Tests/Core/FileCacheHashTests.cs

@@ -14,7 +14,7 @@ namespace React.Tests.Core
 	[TestFixture]
 	public class FileCacheHashTests
 	{
-		private const string SAMPLE_HASH = "B10A8DB164E0754105B7A99BE72E3FE5";
+		private const string SAMPLE_HASH = "0A4D55A8D778E5022FAB701977C5D840BBC486D0";
 
 		[Test]
 		public void TestCalculateHash()