* Update parseHeaders to match node http behavior

Node ignores duplicate entries for certain HTTP headers.

It also always converts the `set-cookie` header into an array.

* add tests for new duplicate header handling

* clarify comment

* Fixing baseURL not working in interceptors

* add test for  modify base URL in request interceptor

Convert the method parameter to lowercase

No buffer in browser

Since the http adapter is never used in the browser it's safe to use
the Buffer global and its isBuffer() method directly.

The is-buffer module checks if an object is a Buffer without causing
Webpack or Browserify to include the whole Buffer module in the bundle.

Include underlying request in errors

Return the last request made in axios response

Update follow-redirects dependency

Using the follow-redirects 1.0.0 causes this reported write after end issue: https://github.com/olalonde/follow-redirects/issues/50. It looks like the problem with follow-redirects was fixed in 1.1.0 https://github.com/olalonde/follow-redirects/commit/9eec6f0fb8d1c51dbd9be732ce1e2c794a01b652 but if axios is going to update the dependency it might as well update to the latest version now.

Header names are lower cased by axios Which make sense since the header names are case insensitive.

Update README.md

Adding templates for issues and pull requests

adding sample code to GET images