fix(style): align navbar-toggle

Changes:
- change `.navbar-toggle` from `margin: 0 -15px 0 0;` to `margin: 0;`

## Before:
- 320x480 ![Screen_Shot_2015-03-19_at_03.43.53](https://gitlab.com/kingcody/gitlab-ce/uploads/376727af07cf62eec5609c01bbbdaacf/Screen_Shot_2015-03-19_at_03.43.53.png)

- 360x640 ![Screen_Shot_2015-03-19_at_03.44.04](https://gitlab.com/kingcody/gitlab-ce/uploads/d5318de4f45687154d90c54f0bece2aa/Screen_Shot_2015-03-19_at_03.44.04.png)

## After:
- 320x480 ![Screen_Shot_2015-03-19_at_03.45.21](https://gitlab.com/kingcody/gitlab-ce/uploads/20f526c9ef19c2c30add001b15c06358/Screen_Shot_2015-03-19_at_03.45.21.png)

- 360x640
![Screen_Shot_2015-03-19_at_03.45.27](https://gitlab.com/kingcody/gitlab-ce/uploads/e60e9dde1f86d89adf36480e7fcc611d/Screen_Shot_2015-03-19_at_03.45.27.png)

See merge request !402