Revert "Use get_availability to determine stream availability"

This reverts commit c209c1f84f.

This commit may have broken downloading/watching by never showing the download button.
Let's see if reverting it fixes the issue. --grin

js/component/file-actions.js

@@ -248,13 +248,13 @@ export let FileActions = React.createClass({
   componentDidMount: function() {
     this._isMounted = true;
     this._fileInfoSubscribeId = lbry.fileInfoSubscribe(this.props.sdHash, this.onFileInfoUpdate);
-    lbry.getStreamAvailability(this.props.streamName, (availability) => {
+    lbry.getPeersForBlobHash(this.props.sdHash, (peers) => {
       if (!this._isMounted) {
         return;
       }
 
       this.setState({
-        available: availability > 0,
+        available: peers.length > 0,
       });
     });
   },

js/lbry.js

@@ -207,10 +207,6 @@ lbry.getPeersForBlobHash = function(blobHash, callback) {
   });
 }
 
-lbry.getStreamAvailability = function(name, callback) {
-  lbry.call('get_availability', {name: name}, callback);
-}
-
 lbry.getCostInfoForName = function(name, callback, errorCallback) {
   /**
    * Takes a LBRY name; will first try and calculate a total cost using