Upcoming change to http.base64decode API

We are going to change the http.base64decode API so that it returns a squirrel blob rather than a string. The motivation is to make it easier to sub-divide a blob into smaller chunks. If you require the output as a string, then electric imp extended squirrel allows you to convert it easily:

`
myblob <- blob(10);
// populate blob.

mystring = blob.tostring();
`
Anyone who has written code that uses http.base64decode may need to tweak it so that it continues to work. Because blobs are implicitly converted to strings in some circumstances, such as server.log(blob), some code may
need no changes at all.