Is your feature request related to a problem? Please describe.
Credential map should be fixed and improved.

Describe the solution you'd like
Credential handling should be refactored into and object with the following fields:

• username
• password
• nt_hash
• ntlm_hash
• ssh_key
• source_node
• origin

Credential map should be refactored in the following way:
0. Credential map should only be displayed when there's valuable information to show.

1. Credential map should contain only nodes that are sources of credentials or are exploited through credential use.
2. Credential map should link nodes in the following way: credential source machine -> machine, exploited with that particular credential.
3. Edge on credential map UI represents a single credential. On edge we should display credential username and credential type, for example MonkeyUser:SSH_key.
4. Edges should be colour coated by their origin: found by monkey or taken from configuration (taken from configuration edges will only start from monkey island)