Support multiple exclusion options

[kato2222]

I fixed issue #2.

Multiple exclusion options are not support by environment variable.
Please review this.

code example:

lane :run_synx do
   synx exclusion: 'Foo'
  synx exclusion: ['Foo', 'Bar']
end

[kirakik]

@afonsograca would be great if you could review this...

[afonsograca]

hey @tero2222,
Thank you for contributing!
Sorry for the delay, I went on holidays the last 2 weeks and was completely offline. I will take a look and merge it ASAP

[afonsograca]

@tero2222 would your solution work for pathnames with spaces in it? don't you think it would be better if you enclose the exclusion in quotes? So that the command would look like this:
$ synx -p --exclusion "/OCMock/Core Mocks" Source/OCMock.xcodeproj/

[kato2222]

@afonsograca Thanks for review!
I think that it would be better to use Shellwords.join().

Example

Shellwords.join([
  "synx",
  "-p",
  "--exclusion",
  "/OCMock/Core Mocks",
  "Source/OCMock.xcodeproj/"])
#=> synx -p --exclusion /OCMock/Core\ Mocks Source/OCMock.xcodeproj/

[kato2222]

I fixed to use shellwords.

d2d10c0

[kato2222]

And separated key and value of exclusion option.

3d3aaed

[afonsograca]

cool! it looks neat!
Just a final remark, can you replace the curly braces {} with do...end on the each loop? Just to keep the ruby code style conventions.

[kato2222]

Thanks!
I fixed the coding style.

3619e0b