Revert correct xpath

Revert xpath changed in [08594a4](https://github.com/samarthgupta437/falcon-regression/commit/08594a4#diff-bb1e70a8ca7f3ab9068582e79c71b134L59) to fix 3 tests from LineageGraphTest
First g-block contains g-blocks with all vertices and paths. If we use `//svg//g` we have extra result (first) witch contains ALL vertices and titles.
![screenshot from 2014-07-15 14 08 28](https://cloud.githubusercontent.com/assets/5871345/3583872/6063df00-0c10-11e4-95eb-0fabcaddc19c.png)