* add zoom image button

* enhance zoom algorithm & add translation

* code structure

* code structure

* code structure

* enhance grab performance

* rm useless state

* fix behavior on Firefox & scroll lock & horizontal scroll with mousewheel

* remove scroll lock on MouseWheelEvent

* code structure

* enhance algorithm and code structure

* rm Gemfile.lock from tree

* codeclimate

* fix a stupid mistake

* Improved media modal

ImageLoader: Impliment pinch zoom by CSS `transform: scale(X)`
ImageLoader: Impliment panning by CSS `overflow: scroll`
ImageLoader: Larger image
MediaModal: Larger close button
MediaModal: Close the modal by swiping vertically
MediaModal: Show/hide close button and right/left navigation on tapping image
MediaModal: Change the `pointer-event` CSS prpp to get more blank space to close the modal
ImageLoader: Zoom/reset zoom on double tap
MediaModal: disable vertical swiping while horizontally swiped
ImageLoader: prevent propagating touchmove event to MediaModal
MediaModal: Adjust size and potision of buttons
ImageLoader: Adjust scroll potision on pinch zoom

* Remove "swipe to close" and "double tap to zoom" features

* remove unused prop and functions

removed `onScroll` prop and `handleScroll` func in ImageLoader

* separate zoom functionary to ZoomableImage component

adjust styling of ImageLoader
add styling for ZoomableImage

* adjust size and potision of close button of media modal

* Fix for gif video

add `onClick` prop to ExtendedVideoPlayer
specify `onClick` prop to video tag for switching nav of `MediaModal`
add `.video-modal` class to scss to separate styling for `VideoModal`

* fix styling for centering

specify height of `ZoomableImage` by pixel
clean styling for `ImageLoader`

* fix lint errors

* small fix

* fixed designated parts

* fix(components/media_modal): Aspect ratio

* fix: Remove useless style

ref https://tc39.github.io/proposal-decorators/

before the full-size image is loaded

* Remove react-imageloader

* add eslint-disable-line

* improve image loading experience

* remove unneeded import

* use PureComponent

* Use componentWillMount instead of constructor