Fix and Configure Repository Migrations for 2.1.15 Release

This configures the Stratum0/1 repository migrations for the release of 2.1.15

Current Migration History:

#### 2.1.6 --> 2.1.7
  * versatile repository upstream descriptors: `local,<tmp dir>,<config string>`
  * shared memory model for upload facility (removed pipe-interface)
  * keeping track of repository creator version

#### 2.1.7+ --> 2.1.15
  * config files changed (adding `client.local`)
  * adjustments in `/etc/fstab`
  * additional statistics counters in file catalogs

#### 2.1.15+
  * TBD (f.e. file size of nested catalogs)