[Owncloud] AppValue back to clob

[Arthur Schiwon]

Hey,

I changed the colum defintion in oc_appconfig.configvalue back to clob.

In the earliest days it was already text 255 which was not enough and we 
changed it to clob; ages ago. This is required by the LDAP backend, 
because it is very likely that we have longer value strings there. And I 
believe to remember that other apps require it as well. It was also 
stated in another thread not long ago that clob is necessary in some places.

Commit is ea3d92cf5d8f237e0b26751abf2f290b42cbb3d2

Cheers
Arthur