initialize-ExecMetadata: Initialize an execution metadata object
In NCEAS/recordr: R Provenance Tracking

Initialize an execution metadata object

## S4 method for signature 'ExecMetadata'
initialize(.Object, executionId = as.character(NA),
  metadataId = as.character(NA), tag = as.character(NA),
  datapackageId = as.character(NA), user = as.character(NA),
  subject = as.character(NA), hostId = as.character(NA),
  startTime = as.character(NA), operatingSystem = as.character(NA),
  runtime = as.character(NA), moduleDependencies = as.character(NA),
  programName = as.character(NA), endTime = as.character(NA),
  errorMessage = as.character(NA), publishTime = as.character(NA),
  publishNodeId = as.character(NA), publishId = as.character(NA),
  console = FALSE, seq = as.integer(0))

`.Object`	The ExecMetada object
`executionId`	a `"character"`, the unique identifier for an execution
`metadataId`	a `"character"`, the unique identifier for the metadata object associated with an execution
`tag`	A character vector that describes this execution.
`datapackageId`	a `"character"`, the unique identifier for the datapackage associated with an execution
`user`	a `"character"`, the user that started the execution
`subject`	a `"character"`, the user identity that owns the uploaded execution datapackage
`hostId`	a `"character"`, the host identifier that the execution datapackage was uploaded to
`startTime`	a `"character"`, the starting time of the execution
`operatingSystem`	a `"character"`, the operating system that the execution ran on
`runtime`	a `"character"`, the software application used for the run, e.g. "R version 3.2.3 (2015-12-10)"
`moduleDependencies`	a `"character"` vector, a list of modules loaded during an execution
`programName`	a `"character"`, The name of the program that is being run.
`endTime`	a `"character"`, the ending time of an execution
`errorMessage`	a `"character"`, error messages generated during an execution
`publishTime`	a `"character"`, the time of publication (uploading) of an execution package
`publishNodeId`	a `"character"`, the node identifier that an execution package was published to
`publishId`	a `"character"`, the unique identifier associated with a published execution
`console`	a `"logical"`, was this execution recorded as commands typed at the console
`seq`	an `"integer"`, an integer associated with an execution