Check installation errors

In case of error the command and status code will be shown.
If --install-error-action=abort the installation will be aborted.
Proper flushing of install logs
Send test specific `Accept` headers
Fix typo in message

There was a typo in a message in the Windows installer script.
Merge pull request #442 from fernandoacorreia/windows-php-typo

Fix typo in message
Merge pull request #428 from fernandoacorreia/install-error-checking

Check installation errors
bumped up Selmer version
Merge pull request #443 from yogthos/patch-1

bumped up Selmer version
Updated aspnet dependencies
Updated mono
Updated NuGet.exe
Servlet: DB test source link
Fix #429: JRuby installation failing

At the time of writing, this will install Maven 3.0.4 on an Ubuntu 12.04 system. Tests indicate that build does not require version 3.0.5, and the official repositories should update as new versions are released.
Fix #431: Composer installation error

By moving Leiningen installation to the top, the bin directory will be created before Composer is installed.
Fix #430: vertx installation error

Download link updated.
Fix  #432: Siena installation error

Tests show that there is no error if the answer is piped from `yes`.
Fix error in __install_client_software

Fixes to run the command in the repository's root directory instead of in 'installs'. Fixes error introduced by commit 7d3f0144ecd7dc5147dca704459f83081272c7fd.
Installer: improve debug messages

grep '^INSTALL' will show the commands and errors without noise.
Standardize commenting style for consistency
Merge pull request #446 from fernandoacorreia/servlet-readme

Servlet: DB test source link