Review/jm netsuite2 updates

[fivetran-joemarkiewicz]

@fivetran-jamie this PR acts as my review of your original PR #41 . Please give the following a thorough review yourself and let me know if you have any questions. A few major items to call out within this PR regarding changes I have made:

• Added all yml and README documentation
• Renamed all variables to be netsuite and netsuite2 specific
• Changed the data_model variable to be netsuite_data_model to make it a bit more descriptive
• Generated all seed data for netsuite2 source and renamed seed data to fit the netsuite and netsuite2 naming convention
• Added a netsuite2_variable_name variable that is to only be used for integration_tests. This way when CircleCi runs, it will run on both netsuite and netsuite2 sources. It also makes sure the entire docs for both sources are generated.
• Updated CHANGELOG

A few places I would like you to take a close eye and make sure my updates are appropriate:

• [x] The entire README
  • Especially the needed tables from Netsuite for netsuite2
• [x] The CHANGELOG entry
• [ ] The grain of the balance sheet and income statement models is quite confusing. I added tests only to the netsuite2 models. I would like to open a FR to recreate these models to be more consistent with our other financial packages.

[fivetran-joemarkiewicz]

FYI I still need to regenerate the docs with the changes from @fivetran-jamie review of the source package. However, I will hold off until this PR is reviewed.