Move global variables out of low-level functions
Removed global variables from getSignature and getOauthFunctionUrl functions,
allowing them to be used without having defined these global variables. This
made it possible to remove workarounds in the user authentication functions,
which use a variety of token key/secret pairs.

This commit also also added a couple of global variables to pass data between
two user-called functions. Otherwise, the user would have to re-enter these
variables by hand. Once used, these temporary global variables are cleared.