Updates to oncotree parser and fix to oncotree_mapping bug

[ovalle15]

• Updates to column labels.
• Updated how we handle logic around different types of liquid tumor parent nodes
• Added logic to add 'No Oncotree Node Found' when parsing the text file
• Fixed bug that included "LIQUID" node to the "SOLID" node.

Note that the differences between the old oncotree_mapping and newly generated oncotree_mapping are differences in order and not in content. The only true difference is the removal of "LIQUID" from the "SOLID" node.