Resolve "Generate Raw RDS file"

Create raw Seurat object with cellranger_count output Includes:

• cellranger filtered cells (cells without background)
• cellranger calculated dimensional reduction:
  • PCA
  • tSNE
  • UMAP (if late enough cellranger version used)
• all cellranger calculated clustering

PR checklist

• This comment contains a description of changes (with reason)
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated
• CHANGELOG.md is updated
• README.md is updated
• LICENSE.md is updated with new contributors

• Close issue
  Closes #50 (closed)

/cc @ghenry

docs/references.md

 ### References
 
 1. **Nextflow**:
-  * Di Tommaso P., Chatzou M., Floden E. W., Barja P. P., Palumbo E., and Notredame C. 2017. Nextflow enables reproducible computational workflows. Nature biotechnology 35(4): 316. doi:[10.1038/nbt.3820](https://doi.org/10.1038/nbt.3820)
+  * Di Tommaso, P., Chatzou, M., Floden, E. W., Barja, P. P., Palumbo, E., & Notredame, C. (2017). Nextflow enables reproducible computational workflows. Nature biotechnology, 35(4), 316-319. doi:[10.1038/nbt.3820](https://doi.org/10.1038/nbt.3820)
 
 2. **cellranger**
   * Cellranger count [https://support.10xgenomics.com/single-cell-gene-expression/software/pipelines/latest/using/count](https://support.10xgenomics.com/single-cell-gene-expression/software/pipelines/latest/using/count)
@@ -9,5 +9,8 @@
 3. **python**:
   * Anaconda (Anaconda Software Distribution, [https://anaconda.com](https://anaconda.com))
 
-4. **MultiQc**:
+4. **Seurat**:
+  * Stuart, T., Butler, A., Hoffman, P., Hafemeister, C., Papalexi, E., Mauck III, W. M., ... & Satija, R. (2019). Comprehensive integration of single-cell data. Cell, 177(7), 1888-1902. doi:[10.1016/j.cell.2019.05.031](https://doi.org/10.1016/j.cell.2019.05.031)
+
+5. **MultiQc**:
   * Ewels P., Magnusson M., Lundin S. and Käller M. 2016. MultiQC: Summarize analysis results for multiple tools and samples in a single report. Bioinformatics 32(19): 3047–3048. doi:[10.1093/bioinformatics/btw354](https://dx.doi.org/10.1093/bioinformatics/btw354)