[FIX] Removed dependency on C++ <filesystem> header, which was causing problems with portability.

src/CSVReader/CSVReader.cpp

-
 #include <string>
 #include <fstream>
 #include <sstream>
-#include <experimental/filesystem>
 #include <regex>
 #include <algorithm>
 #include <memory>
@@ -12,13 +10,17 @@
 #include "CSVReader.h"
 #include "exceptions.h"
 
+bool is_file_accessible(std::string file_path)
+{
+    return std::ifstream(file_path).good();
+}
 
 namespace lib4neuro {
     CSVReader::CSVReader(std::string file_path,
                          std::string delimiter,
                          bool ignore_first_line) {
-        if (!std::experimental::filesystem::exists(file_path)) {
-            THROW_RUNTIME_ERROR("The file path \'" + file_path + "\' specified in CSVReader does not exist!");
+        if (!is_file_accessible(file_path)) {
+            THROW_RUNTIME_ERROR("The file path \'" + file_path + "\' specified in CSVReader is not accessible!");
         }
 
         this->file_path = file_path;