Added Parameter 'size_is_minsize' (true|false(default)) 

Most of the times it desired to specify minimum disk settings for your application stacks (e.g. your web server should have a /var/ww space of 10GB). 

However while during operations individual servers must be manually extended (//var/log is full because of a user error on a single web server of our fleet). For this operations sometimes manually intercepts. However this makes the puppet manifest fail from that moment on. 

If size_is_minsize is set to true, the size parameter is actually a minsize parameter, causing the puppet manifest not to fail, if the LV we found is actually larger then we expected. 

I think this is an essential feature and is needed for opertations at larger scale, expecially with outsourced highly operation teams. 

Even better would be a ensure mode of "minsize", however I was not able to implement this :L)