[maven] add dependency for multipartFile upload
[spring-config] add multipart resolver with 10MiB file size upload limit
[controller] change path from /widgets/{widgetName} to /widget/{widgetName} and change request to POST from PUT
[controller] create process via ProcessBuilder and delete widget dir if something went wrong
[front-end] split widgets.json into multiple corresponding widget.json files
[controller] delete unused import
[gulp] add merge task and some dependencies
[gulp] add merge widgets to build task
[gitignore] ignore widgets.json
[front-end] widgets.json file
[front-end] new lines
[gulp] add gulp-tap to package list
[gulp] move gulp-tap dependency to 'dependencies
Merge branch 'develop' of https://github.com/sochka/wdc into iss40-widget-uploader

Conflicts:
	src/main/webapp/package.json
	src/main/webapp/resources/widgets/widgets.json
[front-end] delete widgets.json
[bug] add missing comma to package.json
Merge branch 'iss40-widget-uploader' of https://github.com/sochka/wdc into iss40-widget-uploader
[npm] use ^ instead of ~, move gulp-extend from devDep to dep
[npm] remove gulp-jsoncombine
[front-end, karma] resolves #76, merge js/main.js & test/unit/test-main.js into js/main.js