linearScoring: Linear Scoring Function
In krumsiek/MoDentify: Phenotype-driven module identification

scores the module in regard to a given phenotype using a linear regression

1	linearScoring(moduleRepresentatives, phenotype, covars)

`moduleRepresentatives`	a `data.table` containing the module representative for each sample as returned by `calculateModuleRepresentatives`
`phenotype`	a vector with the values for a phenotype of interest. It must have the same number of observations as in data.
`covars`	a `data.table` containing the covariates. The rows for the observations must be in the same order as in the phenotype vector.