RW: changed About Ona link in footer

/company to company.ona.io
PLD: catch export fail exceptions
PLD: specifically catch the exceptions
Merge pull request #248 from onaio/catch-sav-except

PLD: catch export fail exceptions
UK: convert date and datetime fields to string for SAV exports, specifically today fields or fields with date type
UK: use six.string_types, for python2/3 compatibility
UK: move encode_if_str out of class methods to make it reusable
UK: encode date strings
UK: encoding of date objects to be optional, csv seem to handle date objects, sav does not
UK: added lines, pretext to rerun travis test
UK: use url name to generate the download json form link
Merge pull request #250 from onaio/sav-date-object-fixes

Sav date object fixes
PLD: add mongo to mac install script
PLD: re-add allow external, install fails (at least) on mac w/o this
PLD: take user as cli arg
PLD: pass user name to install postgis script
PLD: get sav binary from zip file
PLD: rever sav pip changes
Merge pull request #252 from onaio/install-fixes

Install fixes
UK: test generate_qrcode function, add ghostscript to install/ubuntu, closes #251