Merge pull request #8 from ar00/master

I added nci60.prot.R to the branch tmc.NCI60 which shows sparsity of proteomics data (authors could not get any data for certain proteins in certain cell lines). The script also returns heatmaps of protein log(intensity,10) values before/after selecting proteins with log(intensity,10) >=4 in >=5 cell lines. It also plots the average expression of proteins which show the same frequency of N/A values overall cell lines.