New build script for creating packaged libraries

Should just need the one build script (at this point) for building the new libraries.

- Default target (all) builds all of the libraries (Salesforce + Cordova).
- You can build any library individually, by calling e.g. `ant buildSalesforceHybridSDK`.
- Build package output stored in *[Repo Root]*/build/artifacts (as Debug and Relase .zip files).