Upgrade elastic-array to 0.9.0

This is a huge change, which includes some changes to replace code that
originally cloned to reuse allocations instead. The updated
`elastic-array` crate renames its consuming `Vec`-conversion method to
`into_vec`, which means that I can do a simple
`sed -i 's/to_vec/into_vec/'` and then fix the compilation errors.

This commit is probably a minor performance win and definitely a
significant readability win.

local-store/src/lib.rs

@@ -121,7 +121,7 @@ impl TransactionEntry {
 impl From<PendingTransaction> for TransactionEntry {
 	fn from(pending: PendingTransaction) -> Self {
 		TransactionEntry {
-			rlp_bytes: ::rlp::encode(&pending.transaction).to_vec(),
+			rlp_bytes: ::rlp::encode(&pending.transaction).into_vec(),
 			condition: pending.condition.map(Into::into),
 		}
 	}