Adding individual histone writer and eraser reactions to metabolic model

[ScottCampit]

Fill metabolic map and write code to add reactions RECON1 using metabolic map as an xlsx or txt file.

Scott:Get both acetylation and methylation cases

• H3K4
• H3K9

Lauren: methylation cases are a must, acetylation is optional

• H3K27

To pick up later:

• H3K56
• H3K79
• Acetylation cases