Update to more recent version of codegangsta/cli

[langston-barrett]

When updating glide.yaml to use cli version 1.2.0 and attempting to build goss, I get the following error:

# github.com/aelsabbahy/goss
../../add.go:19: c.Duration undefined (type *cli.Context has no field or method Duration)
../../validate.go:26: c.GlobalIsSet undefined (type *cli.Context has no field or method GlobalIsSet)

Distributive uses a more recent version, so I can't take advantage of certain paths in goss code until this is fixed. I'll look into it.

For reference, the current pinned commit is from 2015:

$ git show 70e3fa51ebed95df8c0fbe1519c1c1f9bc16bb13
commit 70e3fa51ebed95df8c0fbe1519c1c1f9bc16bb13
Merge: f445c89 3463964
Author: Jesse Szwedko <[email protected]>
Date:   Thu Oct 29 20:11:27 2015 -0700

[langston-barrett]

Strangely, looks like master has those functions:
https://godoc.org/github.com/codegangsta/cli#Context.Duration

[aelsabbahy]

My recommendation would be to remove cli.Context from places it doesn't need to be.

So for example:

func (sys *System) detectPackage(c *cli.Context)

could be refactored as:

func (sys *System) detectPackage(forcePkg string)

• https://github.com/aelsabbahy/goss/blob/master/system/system.go#L89

For more complex cases, maybe use a config struct that has a collection of attributes in-place of cli.Context