Merge pull request #29 from larshesel/vp

Make ReplaceExistingSeriesTest table driven
Make it possible to run tests in parallel
Merge pull request #30 from gsalgado/vp

Make it possible to run tests in parallel
Move the setting of GOMAXPROCS to the init() function

It doesn't make sense to call it for every test.
Merge pull request #31 from gsalgado/vp

Move the setting of GOMAXPROCS to the init() function
Add restrictions replace and create series

The minimum number of public keys is now three and the number of
required signatures must be less than the number of public keys