depend on crc32fast

We can use this to compute fast checksums to test file integrity (not crypto safe).

Cargo.toml

@@ -49,6 +49,7 @@ xdg = "2.2"
 mio = "0.6"
 valgrind_request = { version = "1.1", optional = true }
 textwrap = "0.11"
+crc32fast = "1"
 
 [features]
 default = []