Relative-navigated imports don't work in SolidityCompiler -- code fix

[3Nigma]

#114 looked at having Contract.allFrom({ path }) variants working when doing .. imports. We need to have import resolution working for Contract.allFrom({ code }) as well.

This raises an interesting question: what is the base-path from which the .. import are resolved when passing in code to compile via SolidityCompiler into Contracts? We might need to add a basePath (or similar) prop to SolidityCompiler.compile to pass that in. If we're going down this path, we might need to bump the release version to 0.9.0 since the rollup-plugin-strato-js package will also need to be updated to a backward incompatible version.