Update azurerm_storage_account's account_type parameter and add public-ip-detect variable

[hantuzun]

• https://github.com/bernadinm/terraform-dcos/commit/72cd305cd29e18e1cabbbba51713f3c95e60cadc: Using Terraform v0.10.7 I had to split azurerm_storage_account's account_type parameter into account_tier and account_replication_type to make the project work. It's documentation is at https://www.terraform.io/docs/providers/azurerm/r/storage_account.html

• https://github.com/bernadinm/terraform-dcos/commit/cd92b5dbc2699c8d3bddf0fc87d3e22b97f075d8: I also wanted to update the .gitigone file to better ignore the files created while working with Terraform and with files to ignore for common operating systems.