Uploading source maps to sentry during build #286

Hi,

Just wondering if anyone has managed to get source map uploads when using https://github.com/arabold/serverless-sentry-plugin and serverless-plugin-typescript to build and deploy ts lambdas. Serverless plugin typescript temporarily creates its outputs in a .build directory but I think this may be deleted after the packaing phase completes in sls and before the sentry plugin runs.