Use /etc/motd to check if a system is OpenBSD

In OpenBSD the first line(s) get overwritten upon each boot by
the rc scripts and kernel informations are added
Fix a small error in an img_id example in the docs

The pithosmap URI needs an image size in the end
Check for python during ./configure

During ./configure check that python >= 2.6 as well as prctl and
scapy python modules are present in the system
docs: Update OS image links
Merge branch 'master' into develop
Bump version to 0.12next
Bump version to 0.12.1
Fix bug in import/export regarding some API params

Fix a bug where API params like CONFIG_URL or IMG_PASSWORD where
checked and used by scripts other that `create' (e.g. `import' and
`export'). This may lead to errors. The CONFIG_URL may not be valid
after the image creation
Merge branch 'hotfix-0.12.1'
Update ChangeLog and version for 0.12.1
Merge branch 'master' into develop

bump version to 0.12.1next

Conflicts:
	version
	version.m4
Add support for enlarging OpenBSD images

This only enlarges the partition and not the ufs file system
Add support for resizing OpenBSD UFS file systems
Run partprobe after diskpart.py

After disklabel.py enlarges the partition the kernel must be
informed about this
Use blockdev instead of partprobe after disklabel

partprobe creates the partitions by itself and since it does not
support disklabels, the disklabel partitons are not recreated
Remount every UFS partition rw just to be sure

In many cases although rw flags is passed to mount, the command
returns SUCCESS with a warning that the fs seems to be mounted ro.
Remounting rw does work.
Fix a bug in disklabel enlarge code

If the disk size is greater that 8G then the CHS value of the MBR
will overflow. We should assign a fixed CHS value for this case.
Minor pep8 error in disklabel.py
Show the partition label in diskpart -l
Remove NUL chars from the output of disklabel.py