gapps init throws error if there is .json manifest file in the project

[vikdet]

Because of Gmail add-ons project has appsmanifest.json file I faced with the following issue:

1. Create an empty Gmail add-ons project.
2. Click View -> Show manifest file
3. execute gapps init 'project_id'
4. See an error:
   Error running init command Unhandled rejection Error: Unsupported file type found at Object.getFileExtension (/home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/lib/util.js:60:9) at writeExternalFile (/home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/lib/commands/init.js:48:35) at /home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/lib/commands/init.js:39:14 at tryCatcher (/home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/node_modules/bluebird/js/main/util.js:26:23) at MappingPromiseArray._promiseFulfilled (/home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/node_modules/bluebird/js/main/map.js:56:38) at MappingPromiseArray.init (/home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/node_modules/bluebird/js/main/promise_array.js:92:18) at Promise._settlePromiseAt (/home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/node_modules/bluebird/js/main/promise.js:582:21) at Promise._settlePromises (/home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/node_modules/bluebird/js/main/promise.js:700:14) at Async._drainQueue (/home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/node_modules/bluebird/js/main/async.js:123:16) at Async._drainQueues (/home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/node_modules/bluebird/js/main/async.js:133:10) at Immediate.Async.drainQueues [as _onImmediate] (/home/vitalybevzik/.nvm/versions/node/v5.12.0/lib/node_modules/node-google-apps-script/node_modules/bluebird/js/main/async.js:15:14) at tryOnImmediate (timers.js:534:15) at processImmediate [as _immediateCallback] (timers.js:514:5)

[vikdet]

MR to resolve this https://github.com/danthareja/node-google-apps-script/pull/59/files

[vietnogi]

Currently, gapps will delete .json files on google drive. I think this fix will also prevent said problem.

[lricoy]

Fixed by #73