Create a Boku API client in Solitude (bug 992376)

- Create an MD5 signer for request signatures
- Parse XML content returned
- Create wrapper methods for interacting with commonly used endpoints
    - Get pricing tiers
    - Start a transaction
    - Check the status of a transaction
Merge pull request #210 from JaredKerim-Mozilla/992376

Create a Boku API client in Solitude (bug 992376)
Add Boku settings to base settings in Solitude (bug 994264)
Merge pull request #211 from JaredKerim-Mozilla/994264

Add Boku settings to base settings in Solitude (bug 994264)
first pass at processing boku callbacks (bug 991581)
bump up suds logging for debugging purposes
Merge pull request #209 from andymckay/991581

first pass at processing boku callbacks (bug 991581)
missing files, i suck
and remove the code in the next patch
suds was causing errors with its own logging
add in verification code (bug 987846)
Merge pull request #213 from andymckay/987846

add in verification code (bug 987846)
Put pay_url on transactions (bug 987839)
Merge pull request #214 from kumar303/pay-url

Put pay_url on transactions (bug 987839)
Implement a start transaction API endpoint in Solitude (bug 987836)

- Create a Boku Transaction Form that wraps the start transaction endpoint in the Boku client
- Create an API View which wraps the form
- Add form and view tests as necessary
Merge pull request #212 from JaredKerim-Mozilla/987836

Implement a start transaction API endpoint in Solitude (bug 987836)
accept JSON in Boku transaction form
Merge pull request #216 from andymckay/fixes

use DATA not POST
Remove merchant_id (bug 994943)

- Remove merchant_id from models, views, clients
- Add BOKU_MERCHANT_ID constant to settings
- Update tests as necessary
Merge pull request #217 from JaredKerim-Mozilla/994943

Remove merchant_id (bug 994943)