Merge pull request #12 from ddemidov/master

Skip fill_char_pair_vector test on AMD
Improve the system::find_default_device() method

This makes some improvements to the system::find_default_device()
method. Now, the devices on the system will only be queried once
when searching for the default device. This reduces the number of
calls to clGetPlatformIDs() and clGetDeviceIDs().

Also, in the case that no GPU or CPU devices are found, the first
device on the system will be selected as the default device. This
fixes issues when using Boost.Compute with pocl.
Fix meta_kernel streaming operators with float

This fixes a bug in the meta_kernel streaming operators with
float values. Now, float scalar and vector literals are inserted
into the kernel source with the proper 'f' suffix.
Remove cv-qualifiers from get<N>()'s value-type

This removes the cv-qualifiers for the value-type returned from
get<N>() expressions. This fixes issues when specializing based
on the type (e.g. pair, tuple).
Add specialization for get<N>() with zip_iterator

This adds a specialization for the get<N>() function when used
with zip_iterator's. Now, only the N'th iterator for the expression
will be dereferenced instead of dereferencing all of the iterators
into a tuple and then extracting the N'th component.
Refactor lambda expression framework to use meta_kernel

This refactors the lambda expression framework to use meta_kernel
to construct kernel source code instead of using plain strings.
Add test for any/all/none_if() with NaN and inf

This adds a test for the any_of(), all_of() and none_of() functions
with NaN and Inf values.
Change meta_kernel::add_arg(name, value) to add_set_arg()

This changes the meta_kernel::add_arg() overload with a name
and a value to a separate method. This fixes conflict when
using add_arg() with string values.
Add type_name<bool>() specialization

This adds a type_name() specialization for bool.
Fix bugs with char/uchar/bool literals in meta_kernel

This fixes a few issues that occurred when using char, uchar
and bool literals with meta_kernel.
Get rid of clang v3.3 warning -Wconstexpr-not-const