Upgrade dependency info in README

I'm new to pallet. Tried following this walkthrough but a lot of the deps were missing (version doesn't exist anymore or groupId changed). These are the problems I found so far.

I had to update `lein pallet up --phases install` to `lein with-profile +pallet pallet up --phases install` or else it complains:

```
Error loading pallet:  Could not locate pallet/main__init.class or pallet/main.clj on classpath:
You need to have pallet as a project dependency.
Exception in thread "main" clojure.lang.ExceptionInfo: Pallet not found as a dependency {:exit-code 1}
```

Even after activating the pallet profile, it errors with:

```
1) org.jclouds.rest.config.SyncToAsyncHttpApiProvider<org.jclouds.rest.HttpClient, A> cannot be used as a key; It is not fully specified.

2) org.jclouds.rest.config.SyncToAsyncHttpApiProvider<org.jclouds.aws.ec2.AWSEC2Client, A> cannot be used as a key; It is not fully specified.

3) org.jclouds.rest.RestContext<org.jclouds.aws.ec2.AWSEC2Client, A> cannot be used as a key; It is not fully specified.

4) No implementation for org.jclouds.rest.HttpClient was bound.
  at org.jclouds.rest.config.BinderUtils.bindHttpApiProvider(BinderUtils.java:109)

5) No implementation for org.jclouds.aws.ec2.AWSEC2Client was bound.
  at org.jclouds.rest.config.BinderUtils.bindHttpApiProvider(BinderUtils.java:109)
```