Revert "validates and serializes cid argument to provide"

This reverts commit a10e3d5.

src/dht/provide.js

@@ -1,7 +1,6 @@
 'use strict'
 
 const promisify = require('promisify-es6')
-const CID = require('cids')
 
 module.exports = (send) => {
   return promisify((cids, opts, callback) => {
@@ -21,13 +20,6 @@ module.exports = (send) => {
       cids = [cids]
     }
 
-    // Validate CID(s) and serialize
-    try {
-      cids = cids.map(cid => new CID(cid).toBaseEncodedString('base58btc'))
-    } catch (err) {
-      return callback(err)
-    }
-
     send({
       path: 'dht/provide',
       args: cids,