[TIMOB-8897] BlackBerry: Implement important Titanium.Blob functionality

* Titanium.Blob * Titanium.Blob.text * Titanium.Blob.toString Implement basic Blob functionality: accessing data, getting size, appending, convert to string. Blobs are primarily used to wrap native data structures or sources (ex: file descriptor, image, buffers). The goal of this ticket is just implement the proxy front facing APIs. Internally it should be architected to support wrapping various data sources. For the initial implementation support "buffer" based blobs would be a good first step. Blobs are not creatable, but returns by various API methods in Titanium. For testing this ticket implement the Buffer.toBlob() method. This should return a Blob which should allocate a buffer and copy the data over. Blob streams and to image conversions will not be implemented at this time. Separate tickets for those will be created.

Acceptance Test

Look into using the test in Anvil for Blobs. The test is currently very small, so try to improve it. Anvil may not run right now on BlackBerry, but we can just copy the test into an application for now.