Errors in setup

[amerritt14]

I'm a Oh-My-ZSH user on a Mac and ran into some problems during setup.
I followed the readme and ran curl https://raw.githubusercontent.com/mykeels/slack-theme-cli/master/slack-theme -O && SLACK_THEME_SHELL_PROFILE=~/.zshrc bash slack-theme install && . ~/.zshrc which placed two lines in my ~/.zshrc file.
When trying to use any of the slack-theme commands, I received an error related to the backup file.

$ slack-theme night
sh: /Users/andrewmerritt/.zshrc
backup file not found

Looking in the backup folder, it was empty. I copied slack's ssb-interop.js file into the backup folder.
cp /Applications/Slack.app/Contents/Resources/app.asar.unpacked/src/static/ssb-interop.js ssb-interop.js

After re-running the command I received a permission error, and slack would report that it crashed, even if it wasn't running.

$ slack-theme night                                                                                       
sh: /Users/andrewmerritt/.zshrc
cp: /Applications/Slack.app/Contents/Resources/app.asar.unpacked/src/static/ssb-interop.js: Permission denied
/Users/andrewmerritt/bin/slack-theme/slack-theme: line 367: /Applications/Slack.app/Contents/Resources/app.asar.unpacked/src/static/ssb-interop.js: Permission denied
No matching processes belonging to you were found

Next I chownd the file throwing the error.
sudo chown andrewmerritt /Applications/Slack.app/Contents/Resources/app.asar.unpacked/src/static/ssb-interop.js

After that everything worked great. I'm happy to put in a PR to update the Readme if you like, or work on getting the backup file created automatically and permission adjusted as needed.

[mykeels]

Thansks for the feedback, @amerritt14

A PR would be most helpful, so others do not experience this.