Better error checking on private key and csr.  Also, pull in file names instead of pointers.
Cleaned up per Kuba.
Restore 'type=file' on privkey and csr command line arguments.
Fixed format string incompatibility with py2.6.
Provide more user-friendly errors when opening file handles.
Read in files with universal newline support.
More sensible mode defaults when creating a unique file.
Work with CSR and private key file contents in the client.
Clarified --rollback command line option.
Updated get_key_csr_pem() to use file contents instead of file names.
Various bug, docstring, and PEP8 fixes.
Merge branch 'master' into file-to-str

Conflicts:
	letsencrypt/client/client.py
	letsencrypt/client/le_util.py
Fixed attribute reference and docstring.
Added in filename support because configuration files still need to reference the correct place
git push origin masterMerge branch 'w0uld-file-to-str'