Merge branch 'release/0.1.0' into develop
be more verbose when failing

If the po file doesn’t contain any module information, compile_po should fail.
May be, this changes in the future and only a warning will be shown, but this
needs a sane default, which we don’t have, yet.
add some more documentation

compile_po task hasn’t been documented, yet. Also a reference to the specs
might be helpful for new users, because these contain some working examples.
Don’t fail if no module name is found

just ignore the string and warn the user.
be more robust on unknown gettext calls

don’t abort and write debug information and info in verbose mode.
be more robust on src files without translatable strings

just ignore those files and print some output about empty files in debug
mode
add more debug output

might be useful when developing with this module.
add more specs about headers option of create_pot task

make sure, everything works, this revealed a bug with parsing the
options. options.headers will now be used, as expected.
bump version
Release version 0.1.1

a simple bug-fix release that brings documentation, more verbose output in
"verbose" and "debug" mode as well as some robustness