Here is my perfectly woring setup of Apache 2.4.7 vhost under Ubuntu 14.04. One thing I cannot get working is openerp-gevent server proxying, so it is commented out in my current config:

<VirtualHost *:443>
    ServerName erp.myserver.zzz
    ServerAdmin webmaster@myserver.zzz

        ProxyPreserveHost On
    ProxyRequests Off

    ProxyErrorOverride On

    # Turn off gzip compression
    #SetEnv no-gzip 1

    # If in any case we get 502 error, lets increase proxy buffer from default 8192 bytes
    ProxyIOBufferSize 16384

        SSLProxyEngine on
        SSLProxyVerify none
        SSLProxyCheckPeerCN off
        SSLProxyCheckPeerName off

        Header set Strict-Transport-Security "max-age=31536000; includeSubDomains"
        RequestHeader set X_FORWARDED_PROTO 'https' env=HTTPS
        RequestHeader set X-Forwarded-Proto "https" env=HTTPS

    <Proxy balancer://odoo-server>
        BalancerMember http://127.0.0.1:8069
        ProxySet lbmethod=byrequests failonstatus=503
    </Proxy>

        ProxyPass / balancer://odoo-server/ timeout=600
        ProxyPassReverse / http://127.0.0.1:8069/ 

    <Proxy balancer://odoo-gevent>
        BalancerMember http://127.0.0.1:8072
        ProxySet lbmethod=byrequests failonstatus=503
    </Proxy>

        ProxyPass /longpolling balancer://odoo-gevent/ timeout=30
        ProxyPassReverse /longpolling http://127.0.0.1:8072/longpolling

    <Location />
        DirectoryIndex index.html
        Options +FollowSymLinks +MultiViews

        AllowOverride AuthConfig Fileinfo Options All
            RewriteEngine On
            RewriteCond %{HTTPS} off
            RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}    
            AuthUserFile /etc/apache2/.htpasswd
            AuthName Hello
            AuthType Basic
            Require user admin
    </Location>

    <LocationMatch "/web/database/manager">
        DirectoryIndex index.html
        Options +FollowSymLinks +MultiViews

        AllowOverride AuthConfig Fileinfo Options All
            RewriteEngine On
            RewriteCond %{HTTPS} off
            RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}    
            AuthUserFile /etc/apache2/.htpasswd
            AuthName Hello
            AuthType Basic
            Require user admin
    </LocationMatch>

    SSLEngine on
    SSLCertificateFile /etc/ssl/certs/wildcard.myserver.zzz.crt
    SSLCertificateKeyFile /etc/ssl/private/wildcard.myserver.zzz.key
    SSLCertificateChainFile /etc/ssl/certs/wildcard.myserver.zzz-ca-bundle.crt 
    SSLOptions +StdEnvVars

    LogLevel warn
    ErrorLog ${APACHE_LOG_DIR}/erp.myserver.zzz-ssl_error.log
    CustomLog ${APACHE_LOG_DIR}/erp.myserver.zzz-ssl_access.log "%V:%p %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x %l %u %t \"%r\" %b %>s %O \"%{Referer}i\" \"%{User-Agent}i\""
</VirtualHost>