Refactored `ramclustR.R` and added a `sample_names` attribute to the `ramclustObj`.

[hechth]

This pull request bundles multiple things

• extracted rc.get.data.csv functionality from ramclustR.R to own function.
• extracted two normalization methods batch.qc and quantile from the ramclustR.R function
• removed duplicate code
• extracted shared code into functions
• implemented function to read data from a data.frame object (currently only MS1 supported)
• harmonized sample name retrieval and storage via sample_names attribute
• added unit tests for most functions Closes #29 Closes #30 Closes #33