Fix up watchman issue with Ghost

# Issue
>>     >>     at BunserBuf.<anonymous> (/home/errong_leng/Ghost/core/client/node_modules/fb-watchman/index.js:95:23)
>>     at emitOne (events.js:116:13)
>>     at BunserBuf.emit (events.js:211:7)
>>     at BunserBuf.process (/home/errong_leng/Ghost/core/client/node_modules/bser/index.js:292:10)
>>     at /home/errong_leng/Ghost/core/client/node_modules/bser/index.js:247:12
>>     at _combinedTickCallback (internal/process/next_tick.js:131:7)
>>     at process._tickCallback (internal/process/next_tick.js:180:9)
>> A non-recoverable condition has triggered.  Watchman needs your help!
>> The triggering condition was at timestamp=1509698956: inotify-add-watch(/home/errong_leng/Ghost/core/client/node_modules/ember-cli-node-assets/node_modules/broccoli-funnel/node_modules/.bin) -> The user limit on the total number of inotify watches was reached; increase the fs.inotify.max_user_watches sysctl
>> All requests will continue to fail with this message until you resolve
>> the underlying problem.  You will find more information on fixing this at
>> https://facebook.github.io/watchman/docs/troubleshooting.html#poison-inotify-add-watch
>> Error: A non-recoverable condition has triggered.  Watchman needs your help!
>> The triggering condition was at timestamp=1509698956: inotify-add-watch(/home/errong_leng/Ghost/core/client/node_modules/ember-cli-node-assets/node_modules/broccoli-funnel/node_modules/.bin) -> The user limit on the total number of inotify watches was reached; increase the fs.inotify.max_user_watches sysctl
>> All requests will continue to fail with this message until you resolve
>> the underlying problem.  You will find more information on fixing this at
>> https://facebook.github.io/watchman/docs/troubleshooting.html#poison-inotify-add-watch
>>

# Solution
sudo su -
echo 8192000 > /proc/sys/fs/inotify/max_user_watches