Change protobuf plugin

[Mykyta]

Due to this issue #39 I can't use this pretty useful docker or I should modify my *.proto files in one package to one proto file.
Can you update your docker by using goprotowrap ?
It'll be very helpful.

[mpnewcomb]

How about you just handle different go_package directories? I mean, is it really that difficult to change the directory of where you output your generated files?

[joyang1]

@Mykyta when you use protowrap to generate go code.
Are you have an error (Error: proto file "" must have a lexicographical prefix of one of the import directories) when generating go code.