Strip newline from base64 encoded auth credentials

The Python str.encode('base64') method wraps lines at 76 characters.
Where the encoded PointHQ credentials are longer than this, the wrapped
line does not conform to the rules for HTTP header continuation as per
RFC2616 [1].

To fix this, remove all newline characters from the encoded
authentication credentials. That is, use a single line for the
Authorization header. This is the same approach used by the Python
Requests library, and by curl.

[1] http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2