Rename from string to from slice and fuck utf8

tests/fromstring.rs

@@ -0,0 +1,19 @@
+extern crate rustijvm;
+
+use rustijvm::binread::BinReadable;
+use std::fs::File;
+use std::io::Read;
+
+#[test]
+fn test_create_from_slice() {
+    let mut vec = Vec::<u8>::new();
+    File::open("files/task1/program1.ijvm").unwrap().read_to_end(&mut vec).unwrap();
+
+    let machine = rustijvm::Machine::new_from_slice(&vec).unwrap();
+    assert_eq!(machine.block.len(), 7);
+    assert_eq!(machine.block[0], 0x10); // BIPUSH
+    assert_eq!(machine.block[2], 0x10); // BIPUSH
+    assert_eq!(machine.block[4], 0x60); // IADD
+    assert_eq!(machine.block[5], 0xFD); // OUT
+}
+