Fix Travis CI build

- Install and use GNU GCC 4.8 to support required C++11 standard
- Build Boost (1.55.0) libraries needed by ledger
- Export build and cmake variables to find locally built Boost

.travis.yml

@@ -1,18 +1,41 @@
+# Since the Travis CI environment (URL) provides GNU GCC 4.6, which does not
+# support -std=c++11 GNU GCC 4.8 is installed. Additionally boost 1.55.0 is
+# compiled from source, since in the Travis CI environment only boost 1.46 is
+# available and no backported package was found on the net.
+
 language: cpp
 compiler:
   - clang
   - gcc
+
+before_install:
+    # Add software package repository, containing updated build toochain, i.e. GNU GCC 4.8
+  - sudo add-apt-repository ppa:ubuntu-toolchain-r/test --yes
+  - sudo apt-get update -qq
+    # Download boost 1.55 and extract the source archive
+  - wget --no-verbose --output-document=boost-trunk.tar.bz2 http://sourceforge.net/projects/boost/files/boost/1.55.0/boost_1_55_0.tar.bz2/download
+  - export BOOST_ROOT="$TRAVIS_BUILD_DIR/../boost-trunk"
+  - export CMAKE_MODULE_PATH="$BOOST_ROOT"
+  - mkdir -p $BOOST_ROOT
+  - tar jxf boost-trunk.tar.bz2 --strip-components=1 -C $BOOST_ROOT
+
 install: 
-  - "./acprep dependencies"
-  - wget http://sourceforge.net/projects/boost/files/boost/1.55.0/boost_1_55_0.tar.bz2/download
-  - tar jxf download
-  - mv boost_1_55_0 $HOME/boost-trunk
+    # Install GNU GCC 4.8 required by use of C++11
+  - sudo apt-get install -qq g++-4.8 gcc-4.8
+  - export CXX="g++-4.8" CC="gcc-4.8"
+    # Build boost libraries required by ledger
+  - (cd $BOOST_ROOT; ./bootstrap.sh --with-libraries=date_time,filesystem,system,iostreams,regex,python,test)
+  - (cd $BOOST_ROOT; ./b2 threading=multi --prefix=$BOOST_ROOT -d0 install)
+    # Install further dependencies
+  - ./acprep dependencies
+
 before_script:
-  - BOOST="$HOME/boost-trunk"
-  - "./acprep opt make --python"
+  - ./acprep opt make --python --boost=$BOOST_ROOT
+
 script:
-  - "./acprep check -- --output-on-failure"
-  - "PYTHONPATH=. python python/demo.py"
+  - ./acprep check -- --output-on-failure
+  - PYTHONPATH=. python python/demo.py
+
 notifications:
   email:
     on_success: change

acprep

@@ -868,6 +868,7 @@ class PrepareBuild(CommandLineApp):
         if self.options.boost_root:
             conf_args.append('-DBOOST_ROOT=%s' %
                              self.options.boost_root)
+            conf_args.append('-DBoost_NO_SYSTEM_PATHS=TRUE')
         if self.options.boost_suffix:
             conf_args.append('-DBoost_COMPILER=%s' %
                              self.options.boost_suffix)