Merge pull request #1 from chahan/convert_svn_to_git

pefile svn to git conversion
Adds MITRE copyright to pefile module
Adds pefile to cybox mappings
Includes more mappings
Moves mappings to separate module
Adds more mappings
Fixes bad comma placement
Replaces commas
Adds NT_HEADERS to PEHeaders mappings
Removes NT_HEADERS that are not mapped in pefile
Adds IMAGE_DATA_DIRECTORY to optional_header_mappings

Reorganizing mappings to reflect pe structures
Removes STRUCT_TYPES from pefile values
Adds data directory struct and data directory mappings
Adds entry export struct and export directory mappings
Fixes a misspelling
Attempts to map cybox.TypedFields
Aligns IMAGE_THUNK_DATA with IMAGE_DESCRIPTOR mappings
Adds IMAGE_IMPORT_BY_NAME mappings
Moves NT_HEADERS comment
Capitalizes DATA_DIRECTORY_STRUCT_MAPPINGS