feature: allow multiple variables and variables with additional text

[gimler]

This allow multiple variables and additional text in arguments.

{{first_param}} and {{second_param}}
my value is {{first_param}}

There are 2 failing testcases:

1. Parametrize Gherkin Feature (Array): Key not exist (exception)
   Test tests/acceptance/GherkinParamArray.feature:Key not exist (exception)
   Step I should see "{{test[9999]}}" is null
   Fail Failed asserting that '' is null.

2. Parametrize Gherkin Feature (Config): Config key not exists (expect null)
   Test tests/acceptance/GherkinParamConfig.feature:Config key not exists (expect null)
   Step I should see "{{config:not_a_param}}" is null
   Fail Failed asserting that '' is null.

What should be the value for {{first_param}} and {{second_param}} when one variable was not set?

I think it would be more logical when the variable not exist. The argument is unchanged. For example

{{config:not_a_param}} would be {{config:not_a_param}} and not null

This way it is also easier to debug when a variable was not set.

[coveralls]

Coverage remained the same at 100.0% when pulling bada880 on gimler:feature/multiple_params into 3ffea94 on edno:master.

[edno]

The change is breaking the test "Config key not exists (expect null)"

[edno]

Hi @gimler,

I support the feature, it makes sense as per the use cases that you've put in the test cases.

For the 'null' case, I still rather keep the current behaviour for missing config key, because there's currently no other way to nullify a parameter (yeah, we can create a special keyword, but that would require extra-parsing).
So, I'll be happy to merge this PR if it does not break the test "Config key not exists (expect null)".

We can then discuss in a separate ticket on how to improve cases like missing config key and null values 😉

[gimler]

@edno the code should reflect the old behavior.

In #23 we should discuss how we can make the not found consistent