make sure that substitutions are numbered when necessary

When there is more than one substitution in a string, Android requires that the
substitutions are explicitly numbered (e.g. %1$s, %2$s, etc.).  This change will
number the substitutions if they are not already numbered.  It just numbers them
from left to right in the string.
strip numbers from substitutions during consume if safe to do so
Fixes incorrect spelling of generate-string-file in help text
Merge pull request #5 from kwood/master

Help text fix
Edited Apple formatter to more closely match the Apple-generated syntax
Cleanup format of generated Apple strings file.

* Remove unnecessary linebreaks.
* Make section headers stand out.
Add Twine version number to generated files.
Update test cases to work with recent formatter changes.
Fix minor README issues.
Ignore dotfiles when consuming localization drops.
Add consume-all-string-files command.
Add the ability to consume comments in a strings file.
Add mention of --consume-comments to the README.
Update version to 0.2.2.
Added formatter for jquery-localize https://github.com/coderifous/jquery-localize.
Cleanup.
Fixup help text to mention all supported string file formats.
Fix testcases to work on Ruby < 1.9.2.
Exit nicely if requiring json fails.
Improve rubyzip error messages.