Improve focus test expression generation

[TaylorOno]

The focus test expression should be the full test description just not just the leaf node.

Describe("loading from JSON", func() {
    Context("when the JSON parses successfully", func() {
        It("should populate the fields correctly", func() {
            Expect(book.Title).To(Equal("Les Miserables"))
         })
     })
})

Will: Generate the focus expression "should populate the fields correctly" Should: Generate the focus expression "loading from JSON when the JSON parses successfully should populate the fields correctly"