Fixed set_cookie max-age parsing

Max-age is expected to be in seconds and thus cannot be parsed by _since_epoch.
Expire attribute is calculated from now() and max-age
Fixed security issues spotted by tom@catalyst.net.nz .
Got the tests working.
Added allow_unsolicited parameter to config class.
Fixing location of 'allow_unknown_attributes' in args lists
Merge pull request #134 from Runscope/master

Fixing location of 'allow_unknown_attributes' in args lists
As Rainer Hörbe pointed out: "A principal is a user, not an entity in SAML. The UnknownPrincipal exception in mdstore.py should be renamed as suggested in the title to avoid confusion.
Unfortunately the OASIS SAML glossary is using the X-811 definition of principal, but contradicts itself otherwise by redefining the term implicitly in other definitions such as Account, Affiliation, IDP, Persistent Pseudonym, etc"
Merge branch 'master' of github.com:rohe/pysaml2
Update request.py
Merge pull request #136 from mdipierro/master

Update request.py. Take care of the possibility no receiver_addrs are defined.
Merge pull request #123 from tpazderka/cookie_expire_fix

Fixed set_cookie max-age parsing
Endpoint index when given must be an integer but stored as a character.
Editorial
Allow kwargs to percolate down through calls. Mark static methods as such.
Corrected documentation.
Merge branch 'master' of github.com:rohe/pysaml2
EOL replacement in certificate read

EOL are replaced in reading the certificate before the split.
Fixes error when certificate has windows EOL.
Removed lower from AttributeConverter

Lower() removed in AttributeConverter methods from_dict and adjust
AttributeConverters should respect the case in the attribute names
according to specifications.
Fixed Attribute_converter

Fixed to_ method as well