make reported_to handling more convenient

Make the reported_to file format less relaxed. See the example:

Bugzilla: URL=http://bugzilla.redhat.com/
^^^^^^^^  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
label   : data

Other changes:
- implement read_entire_reported_to()
- refine functions granularity:
  - provide *_reported_to*_data() functions operating with raw
    reported_to C strings
  - for easier testing
  - required for data stored in problem_data_t
- find_in_reported_to() accepts "label" and not prefix
- add unit test

Related to rhbz#1036585

Signed-off-by: Jakub Filak <jfilak@redhat.com>
make_description: add an option for URLs from reported_to

The option causes that the description text will contain all URLs found
in reported_to file.

For reported_to line:
Bugzilla: URL=http://bugzilla.redhat.com/1000000

the following line will be included in the description:
Bugzilla: http://bugzilla.redhat.com/1000000

Related to rhbz#1036585

Signed-off-by: Jakub Filak <jfilak@redhat.com>
add unit test for make_description (SHOW_URLS)

Related to rhbz#1036585

Signed-off-by: Jakub Filak <jfilak@redhat.com>