Fixing condition of suppressing DOMException caused by XHR Level 2 Incompatible Browsers

Fixing docs for adapters

Updating test for adapter

Proper detection of react-native in isStandardBrowserEnv function

Fixing missing closing paren in node querystring example in README

Adding axios-debug-log to ECOSYSTEM.md

Fixing typo

Adding axios-method-override to ECOSYSTEM.md

Clarifying status of cancelable promises proposal

forEachMehtodNoData => forEachMethodNoData

It's missing an `)`

Change the links of the logos of different browsers according to the original repository.

Fixes #615

Fix upload progress event example

* Fixing combineURLs to support an empty relativeURL

When combining the base and relative URLs, we should forego force
appending a slash to the base when the relative URL is empty.
This leads to a semantic url.

* Fixing combineURLs, allowing single slash relatives

Removing PROTECTION_PREFIX support

Adding a note that several requests can cancelled with the same token.

I asked the question in #516, pretty sure it will help other people too.