feat(remix-tests): add optimization flag to CLI

[adasauce]

Adds an optimize flag to the commander CLI config which generates a
CompilerConfiguration object and passes it down the line to the
compiler optionally.

Running tests on a larger contract without optimization causes it to complain about gas and fail.

running without optimize:

$ remix-tests /tests/test  

        👁       :: Running remix-tests - Unit testing for solidity ::   👁

[18:59:41] info: 1 Solidity test file found
'creation of library remix_accounts.sol:TestsAccounts pending...'
'creation of library remix_tests.sol:Assert pending...'
Error: The contract code couldn't be stored, please check your gas limit.
...

running with optimize:

$ remix-tests --optimize true /tests/test

        👁       :: Running remix-tests - Unit testing for solidity ::   👁

[18:54:48] info: compiler optimization set to undefined
[18:54:48] info: 1 Solidity test file found
'creation of library remix_accounts.sol:TestsAccounts pending...'
'creation of library remix_tests.sol:Assert pending...'

        ◼  Test
        ✓  Test yy owner
        ✓  Test xx roles


2 passing (0.762s)

Fixes #540

[yann300]

this will be handled by #741
Thanks for the PR