Bugfix finds by valere 4

- Updated pre-release version to 7
- no need to send the length of a block when querying for information about the block in a HEAD operation
- Various header fields should be passed around as text and translated to integers
  - ref-count
  - ref-modified
  - block size
- Ref-Modified should be an integer value
Merge pull request #41 from BenjamenMeyer/bugfix_finds_by_valere_4

Bugfix finds by valere 4