Add Eq trait to bit vectors (#17)

For other vector types, you are unable to have Eq because they would be comparing floating point numbers. Bit vectors don't have this problem though and should allow for Eq comparisons.

src/bit.rs

@@ -5,7 +5,7 @@ use crate::diesel_ext::bit::BitType;
 use diesel::{deserialize::FromSqlRow, expression::AsExpression};
 
 /// A bit string.
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 #[cfg_attr(feature = "diesel", derive(FromSqlRow, AsExpression))]
 #[cfg_attr(feature = "diesel", diesel(sql_type = BitType))]
 pub struct Bit {