[AWS|Storage] fixed signed urls when using session tokens

the session token needs to be added to the signature as a header
(as well as being included in the query string)
changed shutdown to reboot in reboot server method
Merge pull request #2443 from fcheung/fix_aws_signed_url

[AWS|Storage] fixed signed urls when using session tokens
fix for broken AWS records tests

see #2439
Update excon dependency to version ~>0.30.0
Merge pull request #2444 from sferik/update_excon_dependency

Update excon dependency to version ~>0.30.0
Fix typo in documentation
[vcloud_director] Fix medias#create - issue #2440
Merge pull request #2447 from sferik/fix_typo

Fix typo in documentation
Merge pull request #2449 from zertico/fixed-reboot-xen-bug

changed shutdown to reboot in reboot server method
Merge pull request #2448 from nosborn/vcloud_director_media_upload

[vcloud_director] Fix medias#create - issue #2440