Add vendor dependencies to composer.json

[csjoblom]

We currently have 2 libraries that we include with our vendor folder that should be handled via composer instead.

• Carbon
• Symphony

AC

• Review the versions we include in the vendor folder
• Add to composer.json
• Once confirmed that composer is installing dependencies correctly, add vendor folder to gitignore

[csjoblom]

@ErikBrown @antonioortegajr we should probably research if these libraries are even necessary and purge them if they are unnecessary.

[csjoblom]

@ralls pinging you as well.