[BUG #7810] allow to bypass the 'export' list of an included config file

- this is necessary if the included config file is narrowing its export list
  so much as to make jobs unusable once they are imported by another config
- (typically the case of end-user config files, which were not designed to be
  included furthermore)
- (but relevant for the synthetic config files of the grunt integration)
[BUG #7810] better temporary names for synthetic config files
[BUG #7810] updated Grunt support for framework/ folder

- the usual framework jobs are now available through 'grunt'