Update Linters

eslint 0.6.2 -> 0.7.4
jscs 1.5.7 -> 1.5.9
Merge pull request #161 from TheAlphaNerd/update-linter

Update Linters
Update CONTRIBUTING.md

Spelling fix - removed unnecessary "by"

# Before 

```
# Contributing to Famo.us

Active involvement from the community is essential to help make famous the most
capable and performant front-end JavaScript framework out there. You can help by
reporting bugs, fixing bugs, adding features, contributing new modules and by
by providing feedback.
```

# After
```
# Contributing to Famo.us

Active involvement from the community is essential to help make famous the most
capable and performant front-end JavaScript framework out there. You can help by
reporting bugs, fixing bugs, adding features, contributing new modules and by
providing feedback.
```
Update CONTRIBUTING.md

Fixed broken link 

# Before
```
If you'd like to contribute a fix for a bug you've encountered, first read up on
[how to report a bug][reporting-bugs-and-other-issues] and report it so we are
aware of the issue.
```
# After
```
If you'd like to contribute a fix for a bug you've encountered, first read up on
[how to report a bug](#reporting-bugs-and-other-issues) and report it so we are
aware of the issue.
```