Removes Boost predicate.hpp dependency

This is a squashed commit that squashes the following commits:

This commit removes the `boost/algorithm/string/predicate.hpp` dependenc
from the project by replacing the function calls to `boost::algorithm::starts_with`
`boost::algorithm::ends_with` and `all` with respectively C++11'
`std::basic_string::front`, `std::basic_string::back`, `std::all_of` function calls

This commit replaces `boost::algorithm::is_digit` with  a locale independent isdigi
function, because the use of the standard library's `isdigit` and `std::isdigit
functions is discoraged in the developer notes

test/lint/lint-includes.sh

@@ -49,7 +49,6 @@ EXPECTED_BOOST_INCLUDES=(
     boost/algorithm/string.hpp
     boost/algorithm/string/case_conv.hpp
     boost/algorithm/string/classification.hpp
-    boost/algorithm/string/predicate.hpp
     boost/algorithm/string/replace.hpp
     boost/algorithm/string/split.hpp
     boost/bind.hpp