CC-5895: Upgrade Propel to 1.7

Used composer to download Propel 1.7
The Propel library will no longer be stored in the Airtime repo
CC-5895: Upgrade Propel to 1.7

Update install scripts with new propel library path
CC-5896: Store cloud files in separate table, inherited from cc_files

Using Class Table Inheritance - delegate behaviour, created a cloud_file
table to store cloud files