soop may not be in the bitcore directory

If bitcore is being built inside of another project that uses soop, soop may
not be in the bitcore directory. We need to find the location of soop and then
find the custom_prelude script relative to that.
Merge pull request #150 from ryanxcharles/bug/fix-soop

soop may not be in the bitcore directory
modularize browser build.js
check submodule validity
add exports
add dir option
fix paths
fix paths
make stdout output possible
remove extra prints
muting testdata for stdout
base dir
fix dir