New configuration parsing from package.json

[ospfranco]

Instead of reading environment variables the configuration now needs to be declared in the package.json:

"op-sqlite": {
  "sqlcipher": true,
  "crsqlite": true,
  "performanceMode": "1",
  "iosSqlite": false,
  "sqliteFlags": "-DSQLITE_DQS=0"
}

This lead to more reproducible builds