fix multiple definition functions

[jeoooo]

ERROR LOGS:

C:\Users\Legion\AppData\Local\Temp\arduino\sketches\B3044CC0048D5D97A6A9AB3D081ED6B2\sketch\PocketbaseExtended.cpp.o: in function `performGETRequest(char const*)':
D:\CODING\pocketbasearduino/PocketbaseExtended.cpp:41: multiple definition of `performGETRequest(char const*)'; C:\Users\Legion\AppData\Local\Temp\arduino\sketches\B3044CC0048D5D97A6A9AB3D081ED6B2\sketch\PocketBaseArduino.cpp.o:D:\CODING\pocketbasearduino/PocketbaseArduino.cpp:41: first defined here
c:/users/legion/appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-4-b40a506/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/bin/ld.exe: C:\Users\Legion\AppData\Local\Temp\arduino\sketches\B3044CC0048D5D97A6A9AB3D081ED6B2\sketch\PocketbaseExtended.cpp.o: in function `performDELETERequest(char const*)':
D:\CODING\pocketbasearduino/PocketbaseExtended.cpp:134: multiple definition of `performDELETERequest(char const*)'; C:\Users\Legion\AppData\Local\Temp\arduino\sketches\B3044CC0048D5D97A6A9AB3D081ED6B2\sketch\PocketBaseArduino.cpp.o:D:\CODING\pocketbasearduino/PocketbaseArduino.cpp:134: first defined here
c:/users/legion/appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-4-b40a506/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/bin/ld.exe: C:\Users\Legion\AppData\Local\Temp\arduino\sketches\B3044CC0048D5D97A6A9AB3D081ED6B2\sketch\PocketbaseExtended.cpp.o: in function `performPOSTRequest(char const*, String const&)':
D:\CODING\pocketbasearduino/PocketbaseExtended.cpp:227: multiple definition of `performPOSTRequest(char const*, String const&)'; C:\Users\Legion\AppData\Local\Temp\arduino\sketches\B3044CC0048D5D97A6A9AB3D081ED6B2\sketch\PocketBaseArduino.cpp.o:D:\CODING\pocketbasearduino/PocketbaseArduino.cpp:227: first defined here