Fix uncaught exceptions

[hugo-dc]

This change removes the following code from the generated js code:

process["on"]("uncaughtException",(function(ex){if(!(ex instanceof ExitStatus)){throw ex}}))

That code was catching all exceptions and for that reason it was showed when whenever other exception occurred in ethereumjs-vm.

Fixes #9

[axic]

Can you make sure those two sed commands actually have at least 1 match? In a future emscripten version the output might be different and they may not replace anything.

In solc-js we had the same issue and ended up not mangling the emscripten output rather having those exceptions listener removed & re-added in a wrapper.

[hugo-dc]

@axic there is a emcc flag (NODEJS_CATCH_EXIT) which avoids generating the code which is currently catching all exceptions. I submitted a new PR #11 including this change and the new generated code.

Regarding the existing sed command in makefile I created a new issue for that and will submit a new PR to validate at least one match.

[hugo-dc]

Created PR #14 to add the sed validation to have at least one match. This PR is no longer necessary.