Add feature : travis-ci pep8 check

This is a great modification, but I think it is very necessary to.

When I read the source code and found that many pep8 norms. Moreover travis-ci are not mandatory, but I think pep8 is the basic requirement, so I added the feature and specification of the current source pep8 solved the problem. Mainly contains the following problem:

```
1. imported modules but unused
2. it is not enough  lines between code
3. redefinition of unused
4. line too long
5. continuation line missing indentation or outdented
6. continuation line under-indented for visual indent

and  so on.
```

But there are some problems such is needed, for example fabric.api, so exhausted that situation I are used `noqa`