Task 3a. Add illumina annotation

[yocra3]

Add annotation from Illumina package to Epimutations. Some interesting fields to be added are:

• Gene
• Gene position
• CpG Island

[yocra3]

This version of the code is thought for using EPIC annotation. Should we make it compatible for 450K array?

[yocra3]

Potential improvement: clean Illumina's gene annotation.

Each CpGs is mapped independently to all transcripts in a gene. Thus, a CpG can be annotated several times to the same gene, even to the same gene position. This can be simplified.