If a key doesn't exist when loading an android file, create it and put it in the "Uncategorized" section
If there's not a default (developer language) translation, warn but still insert it
Make multiline android translations into single line
When reading in a file, if language_code doesn't already exist then add it to the list
Move the row_matches_tag method to stringsfile.rb.
Move another method into the StringsRow class.
Improve ability to import new strings.

We need an easier way to import new strings from a .strings or .xml
file. However, in the normal usecase, we do not want to import
unidentified strings since the strings data file is considered the
master data file and we assume that if it doesn't contain a string that
is found in an input file then that string was recently deleted from the
database.

So, we add a -a option to import all strings we find. We also print
clearer warnings if an unidentified string is found.

Also, clean up some of the code that makes more sense as methods of
StringsFile or StringsRow instead of the abstract formatter class.
Add the ability to write to a separate strings DB.
Fix error handling and option parsing.
Do not print a string that has no tag.

This matches the README description. We really want to encourage users
to use tags. Otherwise it becomes easy to accidentally have a string go
to too many destination files.
Add unit tests.
Replace --tag with --tags.
Fix reference to old method variables.
Update version number to 0.1.2.
Add test files to the gemspec.
Fix gemspec test file.
Properly unescape double quotes in android files.
Support empty translations.

This seems strange, but I can imagine weird scenarios where a key should
translate to nothing in certain languages. So, let's support this for
now.
android-specific improvements

- cross-reference between iOS/Android language/region codes
- support for default languages other than English
- proper escaping of ' and "
- translation between %@ and %s, including numbered parameters (e.g. %1$@)
- proper XML-escaping of < and &
for android, put default language in values folder