Set Accept: application/bitcoin-paymentrequest header

Suggestion from BitPay: set an Accept: HTTP header when
fetching payment requests / payment ACKs.
RPC: add getrawchangeaddress, for raw transaction change destinations
qt: Display txfee in first sendCoinsDialog message box

Signed-off-by: Jonas Schnelli <jonas.schnelli@include7.ch>
Fix typo in a comment: it's base58, not base48.
Merge pull request #2967 from tstranex/master

Fix typo in a comment: it's base58, not base48.
Merge pull request #2958 from laanwj/2013_08_txfee2

[Qt] Display txfee in first sendCoinsDialog message box
Merge pull request #2948 from jgarzik/changeaddr

RPC: add getrawchangeaddress, for raw transaction change destinations
Don't warn about forks while fIsInitialDownload
Merge pull request #2944 from gavinandresen/acceptheader

Set Accept: application/bitcoin-paymentrequest header
Add protobuf 2.5.0 download to gitian release process
Qt 4.8.3 r2 in gitian and release process

Also needed to add `unzip` package for the added unzip command for
OpenSSL in the Qt build.
Make settxfee clear that units are btc/kb.
autotools: switch to autotools buildsystem
Merge pull request #2978 from gmaxwell/rpc_settxfee_doc

Make settxfee clear that units are btc/kb.
Bitcoin-Qt: Use qDebug() for printing to debug.log

- removes all usages of PrintDebugStringF from Qt code
- ensure same format for all debug.log messages "functionname : Message"
qt: add vout index to transaction id in transactions details dialog
Merge pull request #2973 from Diapolo/qDebug

Bitcoin-Qt: Use qDebug() for printing to debug.log
Merge pull request #2976 from laanwj/2013_09_txid_details

qt: add vout index to transaction id in transactions details dialog
Merge pull request #2943 from theuni/autotools-final

Autotools buildsystem
configure.ac: remove superfluous bracket

Reported-by: Cory Fields